81626616 has 96 divisors (see below), whose sum is σ = 231504000. Its totient is φ = 26943840.

The previous prime is 81626591. The next prime is 81626653. The reversal of 81626616 is 61662618.

81626616 is a `hidden beast` number, since 8 + 16 + 26 + 616 = 666.

It is a super-2 number, since 2×81626616² = 13325808879222912, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 386751 + ... + 386961.

It is an arithmetic number, because the mean of its divisors is an integer number (2411500).

Almost surely, 2^81626616 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 81626616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115752000).

81626616 is an abundant number, since it is smaller than the sum of its proper divisors (149877384).

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

81626616 is a wasteful number, since it uses less digits than its factorization.

81626616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431 (or 415 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 81626616 is about 9034.7449327582. The cubic root of 81626616 is about 433.7877305805.

The spelling of 81626616 in words is "eighty-one million, six hundred twenty-six thousand, six hundred sixteen".