21231252 has 72 divisors (see below), whose sum is σ = 61815936. Its totient is φ = 6018624.

The previous prime is 21231241. The next prime is 21231253. The reversal of 21231252 is 25213212.

It is a super-2 number, since 2×21231252² = 901532122975008, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21231253) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 43353 + ... + 43839.

Almost surely, 2^21231252 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 21231252, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30907968).

21231252 is an abundant number, since it is smaller than the sum of its proper divisors (40584684).

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

21231252 is a wasteful number, since it uses less digits than its factorization.

21231252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677 (or 672 counting only the distinct ones).

The product of its digits is 240, while the sum is 18.

The square root of 21231252 is about 4607.7382738172. The cubic root of 21231252 is about 276.9014319977.

Adding to 21231252 its reverse (25213212), we get a palindrome (46444464).

It can be divided in two parts, 2123 and 1252, that added together give a cube (3375 = 15³).

The spelling of 21231252 in words is "twenty-one million, two hundred thirty-one thousand, two hundred fifty-two".