21621700 has 18 divisors (see below), whose sum is σ = 46919306. Its totient is φ = 8648640.

The previous prime is 21621697. The next prime is 21621709. The reversal of 21621700 is 712612.

It can be written as a sum of positive squares in 3 ways, for example, as 4032064 + 17589636 = 2008^2 + 4194^2 .

It is not an unprimeable number, because it can be changed into a prime (21621709) 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 5 ways as a sum of consecutive naturals, for example, 108009 + ... + 108208.

Almost surely, 2^21621700 is an apocalyptic number.

21621700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21621700 is an abundant number, since it is smaller than the sum of its proper divisors (25297606).

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

21621700 is a wasteful number, since it uses less digits than its factorization.

21621700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216231 (or 216224 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21621700 is about 4649.9139776989. The cubic root of 21621700 is about 278.5885603565.

The spelling of 21621700 in words is "twenty-one million, six hundred twenty-one thousand, seven hundred".