81039457065 has 32 divisors (see below), whose sum is σ = 154629328896. Its totient is φ = 35435885760.

The previous prime is 81039457007. The next prime is 81039457087. The reversal of 81039457065 is 56075493018.

It is not a de Polignac number, because 81039457065 - 2⁷ = 81039456937 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16775941 + ... + 16780770.

It is an arithmetic number, because the mean of its divisors is an integer number (4832166528).

Almost surely, 2^81039457065 is an apocalyptic number.

It is an amenable number.

81039457065 is a deficient number, since it is larger than the sum of its proper divisors (73589871831).

81039457065 is a wasteful number, since it uses less digits than its factorization.

81039457065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33556749.

The product of its (nonzero) digits is 907200, while the sum is 48.

The spelling of 81039457065 in words is "eighty-one billion, thirty-nine million, four hundred fifty-seven thousand, sixty-five".