81662697325 has 18 divisors (see below), whose sum is σ = 111304235882. Its totient is φ = 59391050400.

The previous prime is 81662697317. The next prime is 81662697331. The reversal of 81662697325 is 52379626618.

It can be written as a sum of positive squares in 3 ways, for example, as 10083975561 + 71578721764 = 100419^2 + 267542^2 .

It is not a de Polignac number, because 81662697325 - 2³ = 81662697317 is a prime.

It is a super-2 number, since 2×81662697325² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (55).

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 13494942 + ... + 13500991.

Almost surely, 2^81662697325 is an apocalyptic number.

It is an amenable number.

81662697325 is a deficient number, since it is larger than the sum of its proper divisors (29641538557).

81662697325 is a wasteful number, since it uses less digits than its factorization.

81662697325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26995965 (or 26995949 counting only the distinct ones).

The product of its digits is 6531840, while the sum is 55.

The spelling of 81662697325 in words is "eighty-one billion, six hundred sixty-two million, six hundred ninety-seven thousand, three hundred twenty-five".