21699252 has 30 divisors (see below), whose sum is σ = 56726978. Its totient is φ = 7232976.

The previous prime is 21699247. The next prime is 21699253. The reversal of 21699252 is 25299612.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 15968016 + 5731236 = 3996^2 + 2394^2 .

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21699253) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 33163 + ... + 33810.

Almost surely, 2^21699252 is an apocalyptic number.

It is an amenable number.

21699252 is an abundant number, since it is smaller than the sum of its proper divisors (35027726).

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

21699252 is a wasteful number, since it uses less digits than its factorization.

21699252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66989 (or 66978 counting only the distinct ones).

The product of its digits is 19440, while the sum is 36.

The square root of 21699252 is about 4658.2455924951. The cubic root of 21699252 is about 278.9212403425.

The spelling of 21699252 in words is "twenty-one million, six hundred ninety-nine thousand, two hundred fifty-two".