20556331 has 4 divisors (see below), whose sum is σ = 21265200. Its totient is φ = 19847464.

The previous prime is 20556307. The next prime is 20556391. The reversal of 20556331 is 13365502.

It is a happy number.

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 20556331 - 2⁵ = 20556299 is a prime.

It is a super-2 number, since 2×20556331² = 845125488363122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20556296 and 20556305.

It is not an unprimeable number, because it can be changed into a prime (20556301) 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, 354391 + ... + 354448.

It is an arithmetic number, because the mean of its divisors is an integer number (5316300).

Almost surely, 2^20556331 is an apocalyptic number.

20556331 is a deficient number, since it is larger than the sum of its proper divisors (708869).

20556331 is an equidigital number, since it uses as much as digits as its factorization.

20556331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 708868.

The product of its (nonzero) digits is 2700, while the sum is 25.

The square root of 20556331 is about 4533.9090198194. The cubic root of 20556331 is about 273.9356367549.

The spelling of 20556331 in words is "twenty million, five hundred fifty-six thousand, three hundred thirty-one".