21232840 has 32 divisors (see below), whose sum is σ = 47909880. Its totient is φ = 8468992.

The previous prime is 21232829. The next prime is 21232867. The reversal of 21232840 is 4823212.

It can be written as a sum of positive squares in 4 ways, for example, as 11410884 + 9821956 = 3378^2 + 3134^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21804 + ... + 22756.

Almost surely, 2^21232840 is an apocalyptic number.

21232840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21232840 is an abundant number, since it is smaller than the sum of its proper divisors (26677040).

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

21232840 is a wasteful number, since it uses less digits than its factorization.

21232840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1521 (or 1517 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 21232840 is about 4607.9105894103. The cubic root of 21232840 is about 276.9083354768.

The spelling of 21232840 in words is "twenty-one million, two hundred thirty-two thousand, eight hundred forty".