21500253 has 12 divisors (see below), whose sum is σ = 31266300. Its totient is φ = 14236416.

The previous prime is 21500251. The next prime is 21500261. The reversal of 21500253 is 35200512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 870489 + 20629764 = 933^2 + 4542^2 .

It is not a de Polignac number, because 21500253 - 2¹ = 21500251 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21500251) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6676 + ... + 9357.

It is an arithmetic number, because the mean of its divisors is an integer number (2605525).

Almost surely, 2^21500253 is an apocalyptic number.

It is an amenable number.

21500253 is a deficient number, since it is larger than the sum of its proper divisors (9766047).

21500253 is a wasteful number, since it uses less digits than its factorization.

21500253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16188 (or 16185 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 21500253 is about 4636.8365293592. The cubic root of 21500253 is about 278.0659790259.

Adding to 21500253 its reverse (35200512), we get a palindrome (56700765).

The spelling of 21500253 in words is "twenty-one million, five hundred thousand, two hundred fifty-three".