21499900 has 36 divisors (see below), whose sum is σ = 49403088. Its totient is φ = 8093440.

The previous prime is 21499897. The next prime is 21499901. The reversal of 21499900 is 999412.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21499901) 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 11 ways as a sum of consecutive naturals, for example, 4624 + ... + 8023.

It is an arithmetic number, because the mean of its divisors is an integer number (1372308).

Almost surely, 2^21499900 is an apocalyptic number.

21499900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21499900 is an abundant number, since it is smaller than the sum of its proper divisors (27903188).

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

21499900 is a wasteful number, since it uses less digits than its factorization.

21499900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12678 (or 12671 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 21499900 is about 4636.7984644580. The cubic root of 21499900 is about 278.0644572170.

The spelling of 21499900 in words is "twenty-one million, four hundred ninety-nine thousand, nine hundred".