81330857925 has 12 divisors (see below), whose sum is σ = 134467018560. Its totient is φ = 43376457520.

The previous prime is 81330857899. The next prime is 81330857939. The reversal of 81330857925 is 52975803318.

It is a happy number.

It is not a de Polignac number, because 81330857925 - 2¹¹ = 81330855877 is a prime.

It is a super-2 number, since 2×81330857925² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 542205645 + ... + 542205794.

It is an arithmetic number, because the mean of its divisors is an integer number (11205584880).

Almost surely, 2^81330857925 is an apocalyptic number.

It is an amenable number.

81330857925 is a deficient number, since it is larger than the sum of its proper divisors (53136160635).

81330857925 is a wasteful number, since it uses less digits than its factorization.

81330857925 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1084411452 (or 1084411447 counting only the distinct ones).

The product of its (nonzero) digits is 1814400, while the sum is 51.

The spelling of 81330857925 in words is "eighty-one billion, three hundred thirty million, eight hundred fifty-seven thousand, nine hundred twenty-five".