81699908 has 6 divisors (see below), whose sum is σ = 142974846. Its totient is φ = 40849952.

The previous prime is 81699901. The next prime is 81699949. The reversal of 81699908 is 80999618.

It can be written as a sum of positive squares in only one way, i.e., 52301824 + 29398084 = 7232^2 + 5422^2 .

It is not an unprimeable number, because it can be changed into a prime (81699901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10212485 + ... + 10212492.

It is an arithmetic number, because the mean of its divisors is an integer number (23829141).

Almost surely, 2^81699908 is an apocalyptic number.

It is an amenable number.

81699908 is a deficient number, since it is larger than the sum of its proper divisors (61274938).

81699908 is a wasteful number, since it uses less digits than its factorization.

81699908 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20424981 (or 20424979 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 50.

The square root of 81699908 is about 9038.8001416117. The cubic root of 81699908 is about 433.9175234553.

The spelling of 81699908 in words is "eighty-one million, six hundred ninety-nine thousand, nine hundred eight".