20556197 has 4 divisors (see below), whose sum is σ = 20679456. Its totient is φ = 20432940.

The previous prime is 20556191. The next prime is 20556199. The reversal of 20556197 is 79165502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20556197 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20556191) 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 3 ways as a sum of consecutive naturals, for example, 61379 + ... + 61712.

It is an arithmetic number, because the mean of its divisors is an integer number (5169864).

Almost surely, 2^20556197 is an apocalyptic number.

It is an amenable number.

20556197 is a deficient number, since it is larger than the sum of its proper divisors (123259).

20556197 is a wasteful number, since it uses less digits than its factorization.

20556197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123258.

The product of its (nonzero) digits is 18900, while the sum is 35.

The square root of 20556197 is about 4533.8942422602. The cubic root of 20556197 is about 273.9350415213.

The spelling of 20556197 in words is "twenty million, five hundred fifty-six thousand, one hundred ninety-seven".