21723580 has 12 divisors (see below), whose sum is σ = 45619560. Its totient is φ = 8689424.

The previous prime is 21723577. The next prime is 21723589. The reversal of 21723580 is 8532712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21723589) 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, 543070 + ... + 543109.

It is an arithmetic number, because the mean of its divisors is an integer number (3801630).

Almost surely, 2^21723580 is an apocalyptic number.

21723580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21723580 is an abundant number, since it is smaller than the sum of its proper divisors (23895980).

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

21723580 is a wasteful number, since it uses less digits than its factorization.

21723580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1086188 (or 1086186 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 21723580 is about 4660.8561445297. The cubic root of 21723580 is about 279.0254384294.

The spelling of 21723580 in words is "twenty-one million, seven hundred twenty-three thousand, five hundred eighty".