81607897664 has 56 divisors (see below), whose sum is σ = 163342548600. Its totient is φ = 40452194304.

The previous prime is 81607897621. The next prime is 81607897669. The reversal of 81607897664 is 46679870618.

It can be written as a sum of positive squares in 4 ways, for example, as 48396480064 + 33211417600 = 219992^2 + 182240^2 .

It is a super-2 number, since 2×81607897664² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81607897597 and 81607897606.

It is not an unprimeable number, because it can be changed into a prime (81607897669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3607862 + ... + 3630410.

It is an arithmetic number, because the mean of its divisors is an integer number (2916831225).

Almost surely, 2^81607897664 is an apocalyptic number.

It is an amenable number.

81607897664 is an abundant number, since it is smaller than the sum of its proper divisors (81734650936).

81607897664 is a wasteful number, since it uses less digits than its factorization.

81607897664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23047 (or 23037 counting only the distinct ones).

The product of its (nonzero) digits is 24385536, while the sum is 62.

The spelling of 81607897664 in words is "eighty-one billion, six hundred seven million, eight hundred ninety-seven thousand, six hundred sixty-four".