21432580 has 72 divisors (see below), whose sum is σ = 51742152. Its totient is φ = 7428096.

The previous prime is 21432571. The next prime is 21432599. The reversal of 21432580 is 8523412.

It can be written as a sum of positive squares in 12 ways, for example, as 8573184 + 12859396 = 2928^2 + 3586^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 57274 + ... + 57646.

It is an arithmetic number, because the mean of its divisors is an integer number (718641).

Almost surely, 2^21432580 is an apocalyptic number.

21432580 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 21432580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25871076).

21432580 is an abundant number, since it is smaller than the sum of its proper divisors (30309572).

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

21432580 is a wasteful number, since it uses less digits than its factorization.

21432580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425 (or 410 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 21432580 is about 4629.5334538158. The cubic root of 21432580 is about 277.7739307319.

Adding to 21432580 its reverse (8523412), we get a palindrome (29955992).

The spelling of 21432580 in words is "twenty-one million, four hundred thirty-two thousand, five hundred eighty".