81213057328 has 40 divisors (see below), whose sum is σ = 171983363888. Its totient is φ = 36923496192.

The previous prime is 81213057307. The next prime is 81213057347. The reversal of 81213057328 is 82375031218.

It is a happy number.

It is a super-2 number, since 2×81213057328² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2899851 + ... + 2927722.

Almost surely, 2^81213057328 is an apocalyptic number.

It is an amenable number.

81213057328 is an abundant number, since it is smaller than the sum of its proper divisors (90770306560).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81213057328 is a wasteful number, since it uses less digits than its factorization.

81213057328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5827661 (or 5827655 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 40.

The spelling of 81213057328 in words is "eighty-one billion, two hundred thirteen million, fifty-seven thousand, three hundred twenty-eight".