21531252 has 12 divisors (see below), whose sum is σ = 50239616. Its totient is φ = 7177080.

The previous prime is 21531233. The next prime is 21531269. The reversal of 21531252 is 25213512.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 897124 + ... + 897147.

Almost surely, 2^21531252 is an apocalyptic number.

It is an amenable number.

21531252 is an abundant number, since it is smaller than the sum of its proper divisors (28708364).

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

21531252 is a wasteful number, since it uses less digits than its factorization.

21531252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1794278 (or 1794276 counting only the distinct ones).

The product of its digits is 600, while the sum is 21.

The square root of 21531252 is about 4640.1780138266. The cubic root of 21531252 is about 278.1995530812.

Adding to 21531252 its reverse (25213512), we get a palindrome (46744764).

The spelling of 21531252 in words is "twenty-one million, five hundred thirty-one thousand, two hundred fifty-two".