81530913125810 has 64 divisors (see below), whose sum is σ = 147161921718240. Its totient is φ = 32522247014400.

The previous prime is 81530913125759. The next prime is 81530913125821. The reversal of 81530913125810 is 1852131903518.

It is a Cunningham number, because it is equal to 9029447²+1.

It can be written as a sum of positive squares in 16 ways, for example, as 38994442169809 + 42536470956001 = 6244553^2 + 6521999^2 .

It is a super-2 number, since 2×81530913125810² (a number of 29 digits) contains 22 as substring.

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, 24698851160 + ... + 24698854460.

Almost surely, 2^{81530913125810} is an apocalyptic number.

81530913125810 is a deficient number, since it is larger than the sum of its proper divisors (65631008592430).

81530913125810 is a wasteful number, since it uses less digits than its factorization.

81530913125810 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7743.

The product of its (nonzero) digits is 259200, while the sum is 47.

The spelling of 81530913125810 in words is "eighty-one trillion, five hundred thirty billion, nine hundred thirteen million, one hundred twenty-five thousand, eight hundred ten".