21307771 has 2 divisors, whose sum is σ = 21307772. Its totient is φ = 21307770.

The previous prime is 21307753. The next prime is 21307807. The reversal of 21307771 is 17770312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21307771 - 2²³ = 12919163 is a prime.

It is a super-2 number, since 2×21307771² = 908042209976882, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21307271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10653885 + 10653886.

It is an arithmetic number, because the mean of its divisors is an integer number (10653886).

Almost surely, 2^21307771 is an apocalyptic number.

21307771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21307771 is an equidigital number, since it uses as much as digits as its factorization.

21307771 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2058, while the sum is 28.

The square root of 21307771 is about 4616.0341203245. The cubic root of 21307771 is about 277.2336908910.

The spelling of 21307771 in words is "twenty-one million, three hundred seven thousand, seven hundred seventy-one".