20556631 has 4 divisors (see below), whose sum is σ = 20760264. Its totient is φ = 20353000.

The previous prime is 20556619. The next prime is 20556647. The reversal of 20556631 is 13665502.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20556631 - 2¹³ = 20548439 is a prime.

It is a super-2 number, since 2×20556631² = 845150156140322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20556631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20556671) 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, 101665 + ... + 101866.

It is an arithmetic number, because the mean of its divisors is an integer number (5190066).

Almost surely, 2^20556631 is an apocalyptic number.

20556631 is a deficient number, since it is larger than the sum of its proper divisors (203633).

20556631 is a wasteful number, since it uses less digits than its factorization.

20556631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203632.

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 20556631 is about 4533.9421037327. The cubic root of 20556631 is about 273.9369693580.

The spelling of 20556631 in words is "twenty million, five hundred fifty-six thousand, six hundred thirty-one".