21790520 has 32 divisors (see below), whose sum is σ = 50613120. Its totient is φ = 8434560.

The previous prime is 21790519. The next prime is 21790523. The reversal of 21790520 is 2509712.

It is a self number, because there is not a number n which added to its sum of digits gives 21790520.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21790523) 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, 7547 + ... + 10026.

It is an arithmetic number, because the mean of its divisors is an integer number (1581660).

Almost surely, 2^21790520 is an apocalyptic number.

21790520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21790520 is an abundant number, since it is smaller than the sum of its proper divisors (28822600).

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

21790520 is a wasteful number, since it uses less digits than its factorization.

21790520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17615 (or 17611 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 21790520 is about 4668.0317051194. The cubic root of 21790520 is about 279.3117449926.

The spelling of 21790520 in words is "twenty-one million, seven hundred ninety thousand, five hundred twenty".