81616168620 has 240 divisors, whose sum is σ = 292827279360. Its totient is φ = 18641218176.

The previous prime is 81616168583. The next prime is 81616168631. The reversal of 81616168620 is 2686161618.

81616168620 is a `hidden beast` number, since 8 + 1 + 6 + 1 + 6 + 16 + 8 + 620 = 666.

It is a super-2 number, since 2×81616168620² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 30015621 + ... + 30018339.

It is an arithmetic number, because the mean of its divisors is an integer number (1220113664).

Almost surely, 2^81616168620 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 81616168620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (146413639680).

81616168620 is an abundant number, since it is smaller than the sum of its proper divisors (211211110740).

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

81616168620 is a wasteful number, since it uses less digits than its factorization.

81616168620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5394 (or 5383 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 45.

The spelling of 81616168620 in words is "eighty-one billion, six hundred sixteen million, one hundred sixty-eight thousand, six hundred twenty".