21132520 has 16 divisors (see below), whose sum is σ = 47548260. Its totient is φ = 8452992.

The previous prime is 21132509. The next prime is 21132557. The reversal of 21132520 is 2523112.

It can be written as a sum of positive squares in 2 ways, for example, as 21031396 + 101124 = 4586^2 + 318^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21132494 and 21132503.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 264117 + ... + 264196.

Almost surely, 2^21132520 is an apocalyptic number.

21132520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21132520 is an abundant number, since it is smaller than the sum of its proper divisors (26415740).

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

21132520 is a wasteful number, since it uses less digits than its factorization.

21132520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 528324 (or 528320 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21132520 is about 4597.0120730753. The cubic root of 21132520 is about 276.4715386754.

Adding to 21132520 its reverse (2523112), we get a palindrome (23655632).

The spelling of 21132520 in words is "twenty-one million, one hundred thirty-two thousand, five hundred twenty".