81940615972 has 12 divisors (see below), whose sum is σ = 143400767580. Its totient is φ = 40968968096.

The previous prime is 81940615951. The next prime is 81940615997. The reversal of 81940615972 is 27951604918.

It can be written as a sum of positive squares in 2 ways, for example, as 6087744576 + 75852871396 = 78024^2 + 275414^2 .

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 3 ways as a sum of consecutive naturals, for example, 190447 + ... + 447382.

It is an arithmetic number, because the mean of its divisors is an integer number (11950063965).

Almost surely, 2^81940615972 is an apocalyptic number.

It is an amenable number.

81940615972 is a deficient number, since it is larger than the sum of its proper divisors (61460151608).

81940615972 is a wasteful number, since it uses less digits than its factorization.

81940615972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 669950 (or 669948 counting only the distinct ones).

The product of its (nonzero) digits is 1088640, while the sum is 52.

The spelling of 81940615972 in words is "eighty-one billion, nine hundred forty million, six hundred fifteen thousand, nine hundred seventy-two".