21255711 has 4 divisors (see below), whose sum is σ = 28340952. Its totient is φ = 14170472.

The previous prime is 21255679. The next prime is 21255721. The reversal of 21255711 is 11755212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21255711 - 2⁵ = 21255679 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255721) 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, 3542616 + ... + 3542621.

It is an arithmetic number, because the mean of its divisors is an integer number (7085238).

Almost surely, 2^21255711 is an apocalyptic number.

21255711 is a deficient number, since it is larger than the sum of its proper divisors (7085241).

21255711 is an equidigital number, since it uses as much as digits as its factorization.

21255711 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7085240.

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

The square root of 21255711 is about 4610.3916319549. The cubic root of 21255711 is about 277.0077239393.

The spelling of 21255711 in words is "twenty-one million, two hundred fifty-five thousand, seven hundred eleven".