21278532 has 24 divisors (see below), whose sum is σ = 54163872. Its totient is φ = 6448000.

The previous prime is 21278501. The next prime is 21278557. The reversal of 21278532 is 23587212.

It is a self number, because there is not a number n which added to its sum of digits gives 21278532.

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 7 ways as a sum of consecutive naturals, for example, 80469 + ... + 80732.

It is an arithmetic number, because the mean of its divisors is an integer number (2256828).

Almost surely, 2^21278532 is an apocalyptic number.

21278532 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21278532 is an abundant number, since it is smaller than the sum of its proper divisors (32885340).

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

21278532 is a wasteful number, since it uses less digits than its factorization.

21278532 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161219 (or 161217 counting only the distinct ones).

The product of its digits is 6720, while the sum is 30.

The square root of 21278532 is about 4612.8659204447. The cubic root of 21278532 is about 277.1068240862.

The spelling of 21278532 in words is "twenty-one million, two hundred seventy-eight thousand, five hundred thirty-two".