81902978 has 16 divisors (see below), whose sum is σ = 126567360. Its totient is φ = 39720816.

The previous prime is 81902969. The next prime is 81902981. The reversal of 81902978 is 87920918.

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 7 ways as a sum of consecutive naturals, for example, 25025 + ... + 28107.

It is an arithmetic number, because the mean of its divisors is an integer number (7910460).

Almost surely, 2^81902978 is an apocalyptic number.

81902978 is a deficient number, since it is larger than the sum of its proper divisors (44664382).

81902978 is a wasteful number, since it uses less digits than its factorization.

81902978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3481.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 81902978 is about 9050.0264088012. The cubic root of 81902978 is about 434.2767353106.

The spelling of 81902978 in words is "eighty-one million, nine hundred two thousand, nine hundred seventy-eight".