21938771 has 2 divisors, whose sum is σ = 21938772. Its totient is φ = 21938770.

The previous prime is 21938759. The next prime is 21938773. The reversal of 21938771 is 17783912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21938771 is a prime.

Together with 21938773, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21938773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10969385 + 10969386.

It is an arithmetic number, because the mean of its divisors is an integer number (10969386).

Almost surely, 2^21938771 is an apocalyptic number.

21938771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21938771 is an equidigital number, since it uses as much as digits as its factorization.

21938771 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21168, while the sum is 38.

The square root of 21938771 is about 4683.8841787559. The cubic root of 21938771 is about 279.9437429494.

The spelling of 21938771 in words is "twenty-one million, nine hundred thirty-eight thousand, seven hundred seventy-one".