81905256 has 40 divisors (see below), whose sum is σ = 229412370. Its totient is φ = 27301536.

The previous prime is 81905227. The next prime is 81905267. The reversal of 81905256 is 65250918.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 76842756 + 5062500 = 8766^2 + 2250^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 81905256.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 62551 + ... + 63846.

Almost surely, 2^81905256 is an apocalyptic number.

It is an amenable number.

81905256 is an abundant number, since it is smaller than the sum of its proper divisors (147507114).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81905256 is a wasteful number, since it uses less digits than its factorization.

81905256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126415 (or 126402 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 81905256 is about 9050.1522639125. The cubic root of 81905256 is about 434.2807615103.

The spelling of 81905256 in words is "eighty-one million, nine hundred five thousand, two hundred fifty-six".