81640415128 has 8 divisors (see below), whose sum is σ = 153075778380. Its totient is φ = 40820207560.

The previous prime is 81640415113. The next prime is 81640415161. The reversal of 81640415128 is 82151404618.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

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 as a sum of consecutive naturals, namely, 5102525938 + ... + 5102525953.

Almost surely, 2^81640415128 is an apocalyptic number.

It is an amenable number.

81640415128 is a deficient number, since it is larger than the sum of its proper divisors (71435363252).

81640415128 is a wasteful number, since it uses less digits than its factorization.

81640415128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10205051897 (or 10205051893 counting only the distinct ones).

The product of its (nonzero) digits is 61440, while the sum is 40.

The spelling of 81640415128 in words is "eighty-one billion, six hundred forty million, four hundred fifteen thousand, one hundred twenty-eight".