0044

Forty-four is a repdigit and palindromic number in decimal. It is the tenth 10-happy number, and the fourth octahedral number. It is a square-prime of the form p2 × q, and fourth of this form and of the form 22 × q, where q is a higher prime. It is the first member of the first cluster of two square-primes; of the form p2 × q, specifically 22 × 11 = 44 and 32 × 5 = 45. The next such cluster of two square-primes comprises 22 × 29 = 116, and 32 × 13 = 117.