21610720 has 48 divisors (see below), whose sum is σ = 52714368. Its totient is φ = 8363520.

The previous prime is 21610691. The next prime is 21610753. The reversal of 21610720 is 2701612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2782 + ... + 7138.

It is an arithmetic number, because the mean of its divisors is an integer number (1098216).

Almost surely, 2^21610720 is an apocalyptic number.

21610720 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 21610720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26357184).

21610720 is an abundant number, since it is smaller than the sum of its proper divisors (31103648).

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

21610720 is a wasteful number, since it uses less digits than its factorization.

21610720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4403 (or 4395 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21610720 is about 4648.7331607654. The cubic root of 21610720 is about 278.5413944640.

The spelling of 21610720 in words is "twenty-one million, six hundred ten thousand, seven hundred twenty".