21958799 has 2 divisors, whose sum is σ = 21958800. Its totient is φ = 21958798.

The previous prime is 21958759. The next prime is 21958817. The reversal of 21958799 is 99785912.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21958799 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21958709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10979399 + 10979400.

It is an arithmetic number, because the mean of its divisors is an integer number (10979400).

Almost surely, 2^21958799 is an apocalyptic number.

21958799 is a deficient number, since it is larger than the sum of its proper divisors (1).

21958799 is an equidigital number, since it uses as much as digits as its factorization.

21958799 is an evil number, because the sum of its binary digits is even.

The product of its digits is 408240, while the sum is 50.

The square root of 21958799 is about 4686.0216602146. The cubic root of 21958799 is about 280.0289043290.

The spelling of 21958799 in words is "twenty-one million, nine hundred fifty-eight thousand, seven hundred ninety-nine".