21447900 has 54 divisors (see below), whose sum is σ = 67230072. Its totient is φ = 5719200.

The previous prime is 21447871. The next prime is 21447929. The reversal of 21447900 is 974412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21447871) and next prime (21447929).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11016 + ... + 12815.

Almost surely, 2^21447900 is an apocalyptic number.

21447900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21447900 is an abundant number, since it is smaller than the sum of its proper divisors (45782172).

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

21447900 is a wasteful number, since it uses less digits than its factorization.

21447900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23851 (or 23841 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21447900 is about 4631.1877526181. The cubic root of 21447900 is about 277.8400992019.

The spelling of 21447900 in words is "twenty-one million, four hundred forty-seven thousand, nine hundred".