21290752 has 54 divisors (see below), whose sum is σ = 49019208. Its totient is φ = 9040896.

The previous prime is 21290747. The next prime is 21290761. The reversal of 21290752 is 25709212.

It is a super-2 number, since 2×21290752² = 906592241451008, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a self number, because there is not a number n which added to its sum of digits gives 21290752.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 195274 + ... + 195382.

Almost surely, 2^21290752 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21290752, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24509604).

21290752 is an abundant number, since it is smaller than the sum of its proper divisors (27728456).

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

21290752 is an frugal number, since it uses more digits than its factorization.

21290752 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241 (or 118 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21290752 is about 4614.1902864966. The cubic root of 21290752 is about 277.1598602851.

Multiplying 21290752 by its sum of digits (28), we get a square (596141056 = 24416²).

21290752 divided by its sum of digits (28) gives a square (760384 = 872²).

Adding to 21290752 its reverse (25709212), we get a palindrome (46999964).

The spelling of 21290752 in words is "twenty-one million, two hundred ninety thousand, seven hundred fifty-two".