20556900 has 216 divisors, whose sum is σ = 79619904. Its totient is φ = 4320000.

The previous prime is 20556889. The next prime is 20556923. The reversal of 20556900 is 965502.

20556900 is a `hidden beast` number, since 20 + 556 + 90 + 0 = 666.

It is a super-2 number, since 2×20556900² = 845172275220000, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 81775 + ... + 82025.

Almost surely, 2^20556900 is an apocalyptic number.

20556900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20556900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39809952).

20556900 is an abundant number, since it is smaller than the sum of its proper divisors (59063004).

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

20556900 is a wasteful number, since it uses less digits than its factorization.

20556900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291 (or 281 counting only the distinct ones).

The product of its (nonzero) digits is 2700, while the sum is 27.

The square root of 20556900 is about 4533.9717687696. The cubic root of 20556900 is about 273.9381642477.

The spelling of 20556900 in words is "twenty million, five hundred fifty-six thousand, nine hundred".