21258732 has 42 divisors (see below), whose sum is σ = 54564076. Its totient is φ = 6442040.

The previous prime is 21258691. The next prime is 21258733. The reversal of 21258732 is 23785212.

Its product of digits (6720) is a multiple of the sum of its prime divisors (16).

It is a nialpdrome in base 11.

It is a zygodrome in base 11.

It is a self number, because there is not a number n which added to its sum of digits gives 21258732.

It is not an unprimeable number, because it can be changed into a prime (21258733) by changing a digit.

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 13 ways as a sum of consecutive naturals, for example, 1932607 + ... + 1932617.

Almost surely, 2^21258732 is an apocalyptic number.

21258732 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 21258732, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27282038).

21258732 is an abundant number, since it is smaller than the sum of its proper divisors (33305344).

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

21258732 is an frugal number, since it uses more digits than its factorization.

21258732 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73 (or 16 counting only the distinct ones).

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

The square root of 21258732 is about 4610.7192497484. The cubic root of 21258732 is about 277.0208466979.

The spelling of 21258732 in words is "twenty-one million, two hundred fifty-eight thousand, seven hundred thirty-two".