21265771 has 2 divisors, whose sum is σ = 21265772. Its totient is φ = 21265770.

The previous prime is 21265747. The next prime is 21265781. The reversal of 21265771 is 17756212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21265771 - 2⁹ = 21265259 is a prime.

It is not a weakly prime, because it can be changed into another prime (21265781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10632885 + 10632886.

It is an arithmetic number, because the mean of its divisors is an integer number (10632886).

Almost surely, 2^21265771 is an apocalyptic number.

21265771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21265771 is an equidigital number, since it uses as much as digits as its factorization.

21265771 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5880, while the sum is 31.

The square root of 21265771 is about 4611.4825165016. The cubic root of 21265771 is about 277.0514182071.

The spelling of 21265771 in words is "twenty-one million, two hundred sixty-five thousand, seven hundred seventy-one".