81620044 has 12 divisors (see below), whose sum is σ = 155820168. Its totient is φ = 37100000.

The previous prime is 81620041. The next prime is 81620057. The reversal of 81620044 is 44002618.

It is not an unprimeable number, because it can be changed into a prime (81620041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 927457 + ... + 927544.

It is an arithmetic number, because the mean of its divisors is an integer number (12985014).

Almost surely, 2^81620044 is an apocalyptic number.

It is an amenable number.

81620044 is a deficient number, since it is larger than the sum of its proper divisors (74200124).

81620044 is a wasteful number, since it uses less digits than its factorization.

81620044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1855016 (or 1855014 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 25.

The square root of 81620044 is about 9034.3812184344. The cubic root of 81620044 is about 433.7760884241.

The spelling of 81620044 in words is "eighty-one million, six hundred twenty thousand, forty-four".