21963917 has 2 divisors, whose sum is σ = 21963918. Its totient is φ = 21963916.

The previous prime is 21963883. The next prime is 21963947. The reversal of 21963917 is 71936912.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20921476 + 1042441 = 4574^2 + 1021^2 .

It is a cyclic number.

It is not a de Polignac number, because 21963917 - 2⁸ = 21963661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21963947) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10981958 + 10981959.

It is an arithmetic number, because the mean of its divisors is an integer number (10981959).

Almost surely, 2^21963917 is an apocalyptic number.

It is an amenable number.

21963917 is a deficient number, since it is larger than the sum of its proper divisors (1).

21963917 is an equidigital number, since it uses as much as digits as its factorization.

21963917 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20412, while the sum is 38.

The square root of 21963917 is about 4686.5677206246. The cubic root of 21963917 is about 280.0506583512.

The spelling of 21963917 in words is "twenty-one million, nine hundred sixty-three thousand, nine hundred seventeen".