21253648 has 20 divisors (see below), whose sum is σ = 44346988. Its totient is φ = 9809280.

The previous prime is 21253627. The next prime is 21253649. The reversal of 21253648 is 84635212.

It can be written as a sum of positive squares in 2 ways, for example, as 1468944 + 19784704 = 1212^2 + 4448^2 .

It is not an unprimeable number, because it can be changed into a prime (21253649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50883 + ... + 51298.

Almost surely, 2^21253648 is an apocalyptic number.

It is an amenable number.

21253648 is an abundant number, since it is smaller than the sum of its proper divisors (23093340).

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

21253648 is a wasteful number, since it uses less digits than its factorization.

21253648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102202 (or 102196 counting only the distinct ones).

The product of its digits is 11520, while the sum is 31.

The square root of 21253648 is about 4610.1678928213. The cubic root of 21253648 is about 276.9987618707.

The spelling of 21253648 in words is "twenty-one million, two hundred fifty-three thousand, six hundred forty-eight".