21904580 has 12 divisors (see below), whose sum is σ = 45999660. Its totient is φ = 8761824.

The previous prime is 21904559. The next prime is 21904583. The reversal of 21904580 is 8540912.

It can be written as a sum of positive squares in 2 ways, for example, as 11303044 + 10601536 = 3362^2 + 3256^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21904583) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 547595 + ... + 547634.

It is an arithmetic number, because the mean of its divisors is an integer number (3833305).

Almost surely, 2^21904580 is an apocalyptic number.

21904580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21904580 is an abundant number, since it is smaller than the sum of its proper divisors (24095080).

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

21904580 is a wasteful number, since it uses less digits than its factorization.

21904580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1095238 (or 1095236 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 21904580 is about 4680.2329001878. The cubic root of 21904580 is about 279.7982390047.

The spelling of 21904580 in words is "twenty-one million, nine hundred four thousand, five hundred eighty".