81640970 has 32 divisors (see below), whose sum is σ = 157593600. Its totient is φ = 30341376.

The previous prime is 81640943. The next prime is 81640991. The reversal of 81640970 is 7904618.

It is a self number, because there is not a number n which added to its sum of digits gives 81640970.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10391 + ... + 16469.

It is an arithmetic number, because the mean of its divisors is an integer number (4924800).

Almost surely, 2^81640970 is an apocalyptic number.

81640970 is a deficient number, since it is larger than the sum of its proper divisors (75952630).

81640970 is a wasteful number, since it uses less digits than its factorization.

81640970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6182.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 81640970 is about 9035.5392755496. The cubic root of 81640970 is about 433.8131562094.

The spelling of 81640970 in words is "eighty-one million, six hundred forty thousand, nine hundred seventy".