81721249672590 has 48 divisors (see below), whose sum is σ = 231791180892336. Its totient is φ = 19811212041600.

The previous prime is 81721249672549. The next prime is 81721249672627. The reversal of 81721249672590 is 9527694212718.

81721249672590 is a `hidden beast` number, since 8 + 1 + 7 + 21 + 2 + 496 + 72 + 59 + 0 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 41273357431 + ... + 41273359410.

It is an arithmetic number, because the mean of its divisors is an integer number (4828982935257).

Almost surely, 2^{81721249672590} is an apocalyptic number.

81721249672590 is an abundant number, since it is smaller than the sum of its proper divisors (150069931219746).

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

81721249672590 is a wasteful number, since it uses less digits than its factorization.

81721249672590 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82546716865 (or 82546716862 counting only the distinct ones).

The product of its (nonzero) digits is 30481920, while the sum is 63.

The spelling of 81721249672590 in words is "eighty-one trillion, seven hundred twenty-one billion, two hundred forty-nine million, six hundred seventy-two thousand, five hundred ninety".