81708356 has 6 divisors (see below), whose sum is σ = 142989630. Its totient is φ = 40854176.

The previous prime is 81708353. The next prime is 81708391. The reversal of 81708356 is 65380718.

It can be written as a sum of positive squares in only one way, i.e., 77440000 + 4268356 = 8800^2 + 2066^2 .

It is not an unprimeable number, because it can be changed into a prime (81708353) by changing a digit.

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 as a sum of consecutive naturals, namely, 10213541 + ... + 10213548.

It is an arithmetic number, because the mean of its divisors is an integer number (23831605).

Almost surely, 2^81708356 is an apocalyptic number.

It is an amenable number.

81708356 is a deficient number, since it is larger than the sum of its proper divisors (61281274).

81708356 is a wasteful number, since it uses less digits than its factorization.

81708356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20427093 (or 20427091 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 81708356 is about 9039.2674481951. The cubic root of 81708356 is about 433.9324790368.

The spelling of 81708356 in words is "eighty-one million, seven hundred eight thousand, three hundred fifty-six".