81623908 has 6 divisors (see below), whose sum is σ = 142841846. Its totient is φ = 40811952.

The previous prime is 81623903. The next prime is 81623909. The reversal of 81623908 is 80932618.

It can be written as a sum of positive squares in only one way, i.e., 61121124 + 20502784 = 7818^2 + 4528^2 .

It is not an unprimeable number, because it can be changed into a prime (81623903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202985 + ... + 10202992.

Almost surely, 2^81623908 is an apocalyptic number.

It is an amenable number.

81623908 is a deficient number, since it is larger than the sum of its proper divisors (61217938).

81623908 is a wasteful number, since it uses less digits than its factorization.

81623908 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20405981 (or 20405979 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 81623908 is about 9034.5950656352. The cubic root of 81623908 is about 433.7829334925.

The spelling of 81623908 in words is "eighty-one million, six hundred twenty-three thousand, nine hundred eight".