21401900 has 72 divisors (see below), whose sum is σ = 50819664. Its totient is φ = 7776000.

The previous prime is 21401881. The next prime is 21401903. The reversal of 21401900 is 910412.

It is a happy number.

It is a super-2 number, since 2×21401900² = 916082647220000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21401903) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 131219 + ... + 131381.

Almost surely, 2^21401900 is an apocalyptic number.

21401900 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 21401900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25409832).

21401900 is an abundant number, since it is smaller than the sum of its proper divisors (29417764).

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

21401900 is a wasteful number, since it uses less digits than its factorization.

21401900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291 (or 284 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21401900 is about 4626.2187583382. The cubic root of 21401900 is about 277.6413261676.

The spelling of 21401900 in words is "twenty-one million, four hundred one thousand, nine hundred".