21365240 has 64 divisors (see below), whose sum is σ = 52284960. Its totient is φ = 7810560.

The previous prime is 21365233. The next prime is 21365269. The reversal of 21365240 is 4256312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 94007 + ... + 94233.

Almost surely, 2^21365240 is an apocalyptic number.

21365240 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 21365240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26142480).

21365240 is an abundant number, since it is smaller than the sum of its proper divisors (30919720).

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

21365240 is a wasteful number, since it uses less digits than its factorization.

21365240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432 (or 428 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21365240 is about 4622.2548609959. The cubic root of 21365240 is about 277.4827086593.

The spelling of 21365240 in words is "twenty-one million, three hundred sixty-five thousand, two hundred forty".