21163999 has 2 divisors, whose sum is σ = 21164000. Its totient is φ = 21163998.

The previous prime is 21163993. The next prime is 21164029. The reversal of 21163999 is 99936112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21163999 - 2³ = 21163991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21163991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10581999 + 10582000.

It is an arithmetic number, because the mean of its divisors is an integer number (10582000).

Almost surely, 2^21163999 is an apocalyptic number.

21163999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21163999 is an equidigital number, since it uses as much as digits as its factorization.

21163999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 26244, while the sum is 40.

The square root of 21163999 is about 4600.4346533779. The cubic root of 21163999 is about 276.6087478958.

The spelling of 21163999 in words is "twenty-one million, one hundred sixty-three thousand, nine hundred ninety-nine".