81616656 has 80 divisors (see below), whose sum is σ = 231199488. Its totient is φ = 24604800.

The previous prime is 81616651. The next prime is 81616657. The reversal of 81616656 is 65661618.

It is a super-2 number, since 2×81616656² = 13322557073244672, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81616651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 174535 + ... + 175001.

Almost surely, 2^81616656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81616656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115599744).

81616656 is an abundant number, since it is smaller than the sum of its proper divisors (149582832).

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

81616656 is a wasteful number, since it uses less digits than its factorization.

81616656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 820 (or 814 counting only the distinct ones).

The product of its digits is 51840, while the sum is 39.

The square root of 81616656 is about 9034.1937105643. The cubic root of 81616656 is about 433.7700864110.

The spelling of 81616656 in words is "eighty-one million, six hundred sixteen thousand, six hundred fifty-six".