81657708 has 24 divisors (see below), whose sum is σ = 207856320. Its totient is φ = 24744720.

The previous prime is 81657701. The next prime is 81657733. The reversal of 81657708 is 80775618.

It is a self number, because there is not a number n which added to its sum of digits gives 81657708.

It is not an unprimeable number, because it can be changed into a prime (81657701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 309178 + ... + 309441.

It is an arithmetic number, because the mean of its divisors is an integer number (8660680).

Almost surely, 2^81657708 is an apocalyptic number.

It is an amenable number.

81657708 is an abundant number, since it is smaller than the sum of its proper divisors (126198612).

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

81657708 is a wasteful number, since it uses less digits than its factorization.

81657708 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 618637 (or 618635 counting only the distinct ones).

The product of its (nonzero) digits is 94080, while the sum is 42.

The square root of 81657708 is about 9036.4654594592. The cubic root of 81657708 is about 433.8428009186.

The spelling of 81657708 in words is "eighty-one million, six hundred fifty-seven thousand, seven hundred eight".