81565072 has 20 divisors (see below), whose sum is σ = 161888076. Its totient is φ = 39787520.

The previous prime is 81565067. The next prime is 81565073. The reversal of 81565072 is 27056518.

It can be written as a sum of positive squares in 2 ways, for example, as 5456896 + 76108176 = 2336^2 + 8724^2 .

It is not an unprimeable number, because it can be changed into a prime (81565073) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61513 + ... + 62824.

Almost surely, 2^81565072 is an apocalyptic number.

81565072 is a gapful number since it is divisible by the number (82) formed by its first and last digit.

It is an amenable number.

81565072 is a deficient number, since it is larger than the sum of its proper divisors (80323004).

81565072 is a wasteful number, since it uses less digits than its factorization.

81565072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124386 (or 124380 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 34.

The square root of 81565072 is about 9031.3383282878. The cubic root of 81565072 is about 433.6786822259.

The spelling of 81565072 in words is "eighty-one million, five hundred sixty-five thousand, seventy-two".