20216556 has 36 divisors (see below), whose sum is σ = 51243192. Its totient is φ = 6720384.

The previous prime is 20216507. The next prime is 20216569. The reversal of 20216556 is 65561202.

20216556 is a `hidden beast` number, since 2 + 0 + 2 + 1 + 655 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×20216556² = 817418273002272, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20875 + ... + 21821.

It is an arithmetic number, because the mean of its divisors is an integer number (1423422).

Almost surely, 2^20216556 is an apocalyptic number.

It is an amenable number.

20216556 is an abundant number, since it is smaller than the sum of its proper divisors (31026636).

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

20216556 is a wasteful number, since it uses less digits than its factorization.

20216556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1550 (or 1545 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 20216556 is about 4496.2824644366. The cubic root of 20216556 is about 272.4179524610.

Adding to 20216556 its reverse (65561202), we get a palindrome (85777758).

The spelling of 20216556 in words is "twenty million, two hundred sixteen thousand, five hundred fifty-six".