21977771 has 2 divisors, whose sum is σ = 21977772. Its totient is φ = 21977770.

The previous prime is 21977743. The next prime is 21977777. The reversal of 21977771 is 17777912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21977771 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21977777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10988885 + 10988886.

It is an arithmetic number, because the mean of its divisors is an integer number (10988886).

Almost surely, 2^21977771 is an apocalyptic number.

21977771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21977771 is an equidigital number, since it uses as much as digits as its factorization.

21977771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 43218, while the sum is 41.

The square root of 21977771 is about 4688.0455415877. The cubic root of 21977771 is about 280.1095277286.

The spelling of 21977771 in words is "twenty-one million, nine hundred seventy-seven thousand, seven hundred seventy-one".