81957789980 has 48 divisors (see below), whose sum is σ = 188953835616. Its totient is φ = 29612993280.

The previous prime is 81957789961. The next prime is 81957790003. The reversal of 81957789980 is 8998775918.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1151879 + ... + 1220958.

It is an arithmetic number, because the mean of its divisors is an integer number (3936538242).

Almost surely, 2^81957789980 is an apocalyptic number.

It is an amenable number.

81957789980 is an abundant number, since it is smaller than the sum of its proper divisors (106996045636).

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

81957789980 is a wasteful number, since it uses less digits than its factorization.

81957789980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2373014 (or 2373012 counting only the distinct ones).

The product of its (nonzero) digits is 91445760, while the sum is 71.

The spelling of 81957789980 in words is "eighty-one billion, nine hundred fifty-seven million, seven hundred eighty-nine thousand, nine hundred eighty".