253666021 has 16 divisors (see below), whose sum is σ = 294711808. Its totient is φ = 213840000.

The previous prime is 253666019. The next prime is 253666037. The reversal of 253666021 is 120666352.

It is a cyclic number.

It is not a de Polignac number, because 253666021 - 2¹ = 253666019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (253666051) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 337396 + ... + 338146.

It is an arithmetic number, because the mean of its divisors is an integer number (18419488).

Almost surely, 2^253666021 is an apocalyptic number.

It is an amenable number.

253666021 is a deficient number, since it is larger than the sum of its proper divisors (41045787).

253666021 is an equidigital number, since it uses as much as digits as its factorization.

253666021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1492.

The product of its (nonzero) digits is 12960, while the sum is 31.

The square root of 253666021 is about 15926.8961508512. The cubic root of 253666021 is about 633.0248595348.

The spelling of 253666021 in words is "two hundred fifty-three million, six hundred sixty-six thousand, twenty-one".