21000252 has 48 divisors (see below), whose sum is σ = 60311552. Its totient is φ = 5538240.

The previous prime is 21000251. The next prime is 21000269. The reversal of 21000252 is 25200012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000251) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8524 + ... + 10707.

Almost surely, 2^21000252 is an apocalyptic number.

It is an amenable number.

21000252 is an abundant number, since it is smaller than the sum of its proper divisors (39311300).

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

21000252 is a wasteful number, since it uses less digits than its factorization.

21000252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19258 (or 19256 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 12.

The square root of 21000252 is about 4582.6031903275. The cubic root of 21000252 is about 275.8935212034.

Adding to 21000252 its reverse (25200012), we get a palindrome (46200264).

The spelling of 21000252 in words is "twenty-one million, two hundred fifty-two", and thus it is an aban number.