20631636 has 18 divisors (see below), whose sum is σ = 52152282. Its totient is φ = 6877200.

The previous prime is 20631619. The next prime is 20631641. The reversal of 20631636 is 63613602.

20631636 is a `hidden beast` number, since 20 + 6 + 3 + 1 + 636 = 666.

It can be written as a sum of positive squares in only one way, i.e., 20196036 + 435600 = 4494^2 + 660^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 286515 + ... + 286586.

It is an arithmetic number, because the mean of its divisors is an integer number (2897349).

Almost surely, 2^20631636 is an apocalyptic number.

It is an amenable number.

20631636 is an abundant number, since it is smaller than the sum of its proper divisors (31520646).

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

20631636 is a wasteful number, since it uses less digits than its factorization.

20631636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 573111 (or 573106 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 27.

The square root of 20631636 is about 4542.2060719435. The cubic root of 20631636 is about 274.2697363274.

The spelling of 20631636 in words is "twenty million, six hundred thirty-one thousand, six hundred thirty-six".