20631816 has 24 divisors (see below), whose sum is σ = 55878030. Its totient is φ = 6877248.

The previous prime is 20631797. The next prime is 20631817. The reversal of 20631816 is 61813602.

20631816 is a `hidden beast` number, since 20 + 631 + 8 + 1 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 19766916 + 864900 = 4446^2 + 930^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20631816.

It is not an unprimeable number, because it can be changed into a prime (20631817) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 143205 + ... + 143348.

Almost surely, 2^20631816 is an apocalyptic number.

It is an amenable number.

20631816 is an abundant number, since it is smaller than the sum of its proper divisors (35246214).

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

20631816 is a wasteful number, since it uses less digits than its factorization.

20631816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 286565 (or 286558 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 20631816 is about 4542.2258860607. The cubic root of 20631816 is about 274.2705339441.

The spelling of 20631816 in words is "twenty million, six hundred thirty-one thousand, eight hundred sixteen".