21413720 has 32 divisors (see below), whose sum is σ = 48686400. Its totient is φ = 8475648.

The previous prime is 21413719. The next prime is 21413729. The reversal of 21413720 is 2731412.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21413692 and 21413701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21413729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1121 + ... + 6639.

It is an arithmetic number, because the mean of its divisors is an integer number (1521450).

Almost surely, 2^21413720 is an apocalyptic number.

21413720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21413720 is an abundant number, since it is smaller than the sum of its proper divisors (27272680).

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

21413720 is a wasteful number, since it uses less digits than its factorization.

21413720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5627 (or 5623 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21413720 is about 4627.4960831966. The cubic root of 21413720 is about 277.6924293642.

The spelling of 21413720 in words is "twenty-one million, four hundred thirteen thousand, seven hundred twenty".