20815816 has 32 divisors (see below), whose sum is σ = 44778240. Its totient is φ = 8886528.

The previous prime is 20815807. The next prime is 20815831. The reversal of 20815816 is 61851802.

It is a super-3 number, since 3×20815816³ (a number of 23 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18321 + ... + 19423.

It is an arithmetic number, because the mean of its divisors is an integer number (1399320).

Almost surely, 2^20815816 is an apocalyptic number.

It is an amenable number.

20815816 is an abundant number, since it is smaller than the sum of its proper divisors (23962424).

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

20815816 is a wasteful number, since it uses less digits than its factorization.

20815816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1453 (or 1449 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 20815816 is about 4562.4353146100. The cubic root of 20815816 is about 275.0834611688.

The spelling of 20815816 in words is "twenty million, eight hundred fifteen thousand, eight hundred sixteen".