21392910 has 200 divisors, whose sum is σ = 73206936. Its totient is φ = 4445280.

The previous prime is 21392893. The next prime is 21392929. The reversal of 21392910 is 1929312.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a zygodrome in base 9.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 99 ways as a sum of consecutive naturals, for example, 1944805 + ... + 1944815.

Almost surely, 2^21392910 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21392910, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36603468).

21392910 is an abundant number, since it is smaller than the sum of its proper divisors (51814026).

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

21392910 is an equidigital number, since it uses as much as digits as its factorization.

21392910 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58 (or 28 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 21392910 is about 4625.2470204304. The cubic root of 21392910 is about 277.6024457397.

The spelling of 21392910 in words is "twenty-one million, three hundred ninety-two thousand, nine hundred ten".