21941399 has 2 divisors, whose sum is σ = 21941400. Its totient is φ = 21941398.

The previous prime is 21941393. The next prime is 21941401. The reversal of 21941399 is 99314912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21941399 is a prime.

Together with 21941401, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21941393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10970699 + 10970700.

It is an arithmetic number, because the mean of its divisors is an integer number (10970700).

Almost surely, 2^21941399 is an apocalyptic number.

21941399 is a deficient number, since it is larger than the sum of its proper divisors (1).

21941399 is an equidigital number, since it uses as much as digits as its factorization.

21941399 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17496, while the sum is 38.

The square root of 21941399 is about 4684.1647067540. The cubic root of 21941399 is about 279.9549204637.

The spelling of 21941399 in words is "twenty-one million, nine hundred forty-one thousand, three hundred ninety-nine".