81620040 has 64 divisors (see below), whose sum is σ = 245606400. Its totient is φ = 21699072.

The previous prime is 81620027. The next prime is 81620041. The reversal of 81620040 is 4002618.

It is a junction number, because it is equal to n+sod(n) for n = 81619989 and 81620016.

It is not an unprimeable number, because it can be changed into a prime (81620041) 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 15 ways as a sum of consecutive naturals, for example, 48249 + ... + 49911.

It is an arithmetic number, because the mean of its divisors is an integer number (3837600).

Almost surely, 2^81620040 is an apocalyptic number.

It is an amenable number.

81620040 is an abundant number, since it is smaller than the sum of its proper divisors (163986360).

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

81620040 is a wasteful number, since it uses less digits than its factorization.

81620040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2086 (or 2082 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 81620040 is about 9034.3809970579. The cubic root of 81620040 is about 433.7760813380.

Adding to 81620040 its reverse (4002618), we get a palindrome (85622658).

The spelling of 81620040 in words is "eighty-one million, six hundred twenty thousand, forty".