21253568 has 28 divisors (see below), whose sum is σ = 48201072. Its totient is φ = 9108480.

The previous prime is 21253543. The next prime is 21253591. The reversal of 21253568 is 86535212.

It is a tau number, because it is divible by the number of its divisors (28).

It is a Harshad number since it is a multiple of its sum of digits (32).

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, 23273 + ... + 24168.

Almost surely, 2^21253568 is an apocalyptic number.

21253568 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21253568 is an abundant number, since it is smaller than the sum of its proper divisors (26947504).

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

21253568 is an equidigital number, since it uses as much as digits as its factorization.

21253568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47460 (or 47450 counting only the distinct ones).

The product of its digits is 14400, while the sum is 32.

The square root of 21253568 is about 4610.1592163395. The cubic root of 21253568 is about 276.9984143236.

The spelling of 21253568 in words is "twenty-one million, two hundred fifty-three thousand, five hundred sixty-eight".