21919771 has 2 divisors, whose sum is σ = 21919772. Its totient is φ = 21919770.

The previous prime is 21919763. The next prime is 21919811. The reversal of 21919771 is 17791912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21919771 - 2³ = 21919763 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21919771.

It is not a weakly prime, because it can be changed into another prime (21919741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10959885 + 10959886.

It is an arithmetic number, because the mean of its divisors is an integer number (10959886).

Almost surely, 2^21919771 is an apocalyptic number.

21919771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21919771 is an equidigital number, since it uses as much as digits as its factorization.

21919771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7938, while the sum is 37.

The square root of 21919771 is about 4681.8555082360. The cubic root of 21919771 is about 279.8629048244.

The spelling of 21919771 in words is "twenty-one million, nine hundred nineteen thousand, seven hundred seventy-one".