81689136 has 20 divisors (see below), whose sum is σ = 211030392. Its totient is φ = 27229696.

The previous prime is 81689129. The next prime is 81689171. The reversal of 81689136 is 63198618.

It is a super-2 number, since 2×81689136² = 13346229880852992, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 850881 + ... + 850976.

Almost surely, 2^81689136 is an apocalyptic number.

It is an amenable number.

81689136 is an abundant number, since it is smaller than the sum of its proper divisors (129341256).

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

81689136 is a wasteful number, since it uses less digits than its factorization.

81689136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1701868 (or 1701862 counting only the distinct ones).

The product of its digits is 62208, while the sum is 42.

The square root of 81689136 is about 9038.2042464197. The cubic root of 81689136 is about 433.8984521772.

The spelling of 81689136 in words is "eighty-one million, six hundred eighty-nine thousand, one hundred thirty-six".