20981900 has 18 divisors (see below), whose sum is σ = 45530940. Its totient is φ = 8392720.

The previous prime is 20981899. The next prime is 20981929. The reversal of 20981900 is 918902.

It is a super-2 number, since 2×20981900² = 880480255220000, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 104810 + ... + 105009.

Almost surely, 2^20981900 is an apocalyptic number.

20981900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20981900 is an abundant number, since it is smaller than the sum of its proper divisors (24549040).

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

20981900 is a wasteful number, since it uses less digits than its factorization.

20981900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209833 (or 209826 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 29.

The square root of 20981900 is about 4580.6003973278. The cubic root of 20981900 is about 275.8131305249.

The spelling of 20981900 in words is "twenty million, nine hundred eighty-one thousand, nine hundred".