21387700 has 72 divisors (see below), whose sum is σ = 51371712. Its totient is φ = 7687680.

The previous prime is 21387697. The next prime is 21387701. The reversal of 21387700 is 778312.

It is a happy number.

It is a super-2 number, since 2×21387700² = 914867422580000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21387701) 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, 38827 + ... + 39373.

It is an arithmetic number, because the mean of its divisors is an integer number (713496).

Almost surely, 2^21387700 is an apocalyptic number.

21387700 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 21387700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25685856).

21387700 is an abundant number, since it is smaller than the sum of its proper divisors (29984012).

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

21387700 is a wasteful number, since it uses less digits than its factorization.

21387700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 601 (or 594 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 21387700 is about 4624.6837729730. The cubic root of 21387700 is about 277.5799082702.

The spelling of 21387700 in words is "twenty-one million, three hundred eighty-seven thousand, seven hundred".