81617688 has 24 divisors (see below), whose sum is σ = 221048100. Its totient is φ = 27205872.

The previous prime is 81617681. The next prime is 81617689. The reversal of 81617688 is 88671618.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×81617688² = 13322893988930688, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81617681) 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 in 5 ways as a sum of consecutive naturals, for example, 566718 + ... + 566861.

Almost surely, 2^81617688 is an apocalyptic number.

It is an amenable number.

81617688 is an abundant number, since it is smaller than the sum of its proper divisors (139430412).

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

81617688 is a wasteful number, since it uses less digits than its factorization.

81617688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1133591 (or 1133584 counting only the distinct ones).

The product of its digits is 129024, while the sum is 45.

The square root of 81617688 is about 9034.2508267150. The cubic root of 81617688 is about 433.7719146687.

The spelling of 81617688 in words is "eighty-one million, six hundred seventeen thousand, six hundred eighty-eight".