21688700 has 36 divisors (see below), whose sum is σ = 51345672. Its totient is φ = 7886400.

The previous prime is 21688699. The next prime is 21688703. The reversal of 21688700 is 788612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21688703) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8759 + ... + 10958.

Almost surely, 2^21688700 is an apocalyptic number.

21688700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21688700 is an abundant number, since it is smaller than the sum of its proper divisors (29656972).

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

21688700 is a wasteful number, since it uses less digits than its factorization.

21688700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19742 (or 19735 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 21688700 is about 4657.1128395176. The cubic root of 21688700 is about 278.8760213625.

The spelling of 21688700 in words is "twenty-one million, six hundred eighty-eight thousand, seven hundred".