20215556 has 6 divisors (see below), whose sum is σ = 35377230. Its totient is φ = 10107776.

The previous prime is 20215543. The next prime is 20215561. The reversal of 20215556 is 65551202.

It can be written as a sum of positive squares in only one way, i.e., 19945156 + 270400 = 4466^2 + 520^2 .

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 as a sum of consecutive naturals, namely, 2526941 + ... + 2526948.

It is an arithmetic number, because the mean of its divisors is an integer number (5896205).

Almost surely, 2^20215556 is an apocalyptic number.

It is an amenable number.

20215556 is a deficient number, since it is larger than the sum of its proper divisors (15161674).

20215556 is a wasteful number, since it uses less digits than its factorization.

20215556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5053893 (or 5053891 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 26.

The square root of 20215556 is about 4496.1712600834. The cubic root of 20215556 is about 272.4134607226.

Adding to 20215556 its reverse (65551202), we get a palindrome (85766758).

The spelling of 20215556 in words is "twenty million, two hundred fifteen thousand, five hundred fifty-six".