21255117 has 16 divisors (see below), whose sum is σ = 32316480. Its totient is φ = 12310272.

The previous prime is 21255107. The next prime is 21255127. The reversal of 21255117 is 71155212.

It is an interprime number because it is at equal distance from previous prime (21255107) and next prime (21255127).

It is not a de Polignac number, because 21255117 - 2⁸ = 21254861 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255107) 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, 15367 + ... + 16692.

It is an arithmetic number, because the mean of its divisors is an integer number (2019780).

Almost surely, 2^21255117 is an apocalyptic number.

It is an amenable number.

21255117 is a deficient number, since it is larger than the sum of its proper divisors (11061363).

21255117 is a wasteful number, since it uses less digits than its factorization.

21255117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32092.

The product of its digits is 700, while the sum is 24.

The square root of 21255117 is about 4610.3272118148. The cubic root of 21255117 is about 277.0051435486.

The spelling of 21255117 in words is "twenty-one million, two hundred fifty-five thousand, one hundred seventeen".