21655252 has 6 divisors (see below), whose sum is σ = 37896698. Its totient is φ = 10827624.

The previous prime is 21655247. The next prime is 21655321. The reversal of 21655252 is 25255612.

It can be written as a sum of positive squares in only one way, i.e., 15335056 + 6320196 = 3916^2 + 2514^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21655252.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 2706903 + ... + 2706910.

Almost surely, 2^21655252 is an apocalyptic number.

It is an amenable number.

21655252 is a deficient number, since it is larger than the sum of its proper divisors (16241446).

21655252 is a wasteful number, since it uses less digits than its factorization.

21655252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5413817 (or 5413815 counting only the distinct ones).

The product of its digits is 6000, while the sum is 28.

The square root of 21655252 is about 4653.5203878354. The cubic root of 21655252 is about 278.7325880790.

The spelling of 21655252 in words is "twenty-one million, six hundred fifty-five thousand, two hundred fifty-two".