21105252 has 48 divisors (see below), whose sum is σ = 62536320. Its totient is φ = 6029856.

The previous prime is 21105239. The next prime is 21105307. The reversal of 21105252 is 25250112.

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13203 + ... + 14714.

It is an arithmetic number, because the mean of its divisors is an integer number (1302840).

Almost surely, 2^21105252 is an apocalyptic number.

It is an amenable number.

21105252 is an abundant number, since it is smaller than the sum of its proper divisors (41431068).

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

21105252 is a wasteful number, since it uses less digits than its factorization.

21105252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27937 (or 27929 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21105252 is about 4594.0452762244. The cubic root of 21105252 is about 276.3525739901.

Adding to 21105252 its reverse (25250112), we get a palindrome (46355364).

The spelling of 21105252 in words is "twenty-one million, one hundred five thousand, two hundred fifty-two".