81464865 has 16 divisors (see below), whose sum is σ = 133118208. Its totient is φ = 42523136.

The previous prime is 81464849. The next prime is 81464891. The reversal of 81464865 is 56846418.

It is a cyclic number.

It is not a de Polignac number, because 81464865 - 2⁴ = 81464849 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57072 + ... + 58481.

It is an arithmetic number, because the mean of its divisors is an integer number (8319888).

Almost surely, 2^81464865 is an apocalyptic number.

It is an amenable number.

81464865 is a deficient number, since it is larger than the sum of its proper divisors (51653343).

81464865 is a wasteful number, since it uses less digits than its factorization.

81464865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115608.

The product of its digits is 184320, while the sum is 42.

The square root of 81464865 is about 9025.7888851889. The cubic root of 81464865 is about 433.5010103889.

The spelling of 81464865 in words is "eighty-one million, four hundred sixty-four thousand, eight hundred sixty-five".