21357732 has 48 divisors (see below), whose sum is σ = 55847232. Its totient is φ = 6295680.

The previous prime is 21357719. The next prime is 21357773. The reversal of 21357732 is 23775312.

It is a self number, because there is not a number n which added to its sum of digits gives 21357732.

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 15 ways as a sum of consecutive naturals, for example, 2698 + ... + 7070.

It is an arithmetic number, because the mean of its divisors is an integer number (1163484).

Almost surely, 2^21357732 is an apocalyptic number.

21357732 is a gapful number since it is divisible by the number (22) 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 21357732, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27923616).

21357732 is an abundant number, since it is smaller than the sum of its proper divisors (34489500).

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

21357732 is a wasteful number, since it uses less digits than its factorization.

21357732 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4428 (or 4426 counting only the distinct ones).

The product of its digits is 8820, while the sum is 30.

The square root of 21357732 is about 4621.4426319062. The cubic root of 21357732 is about 277.4502012741.

It can be divided in two parts, 21 and 357732, that added together give a palindrome (357753).

The spelling of 21357732 in words is "twenty-one million, three hundred fifty-seven thousand, seven hundred thirty-two".