21199999 has 2 divisors, whose sum is σ = 21200000. Its totient is φ = 21199998.

The previous prime is 21199973. The next prime is 21200021. The reversal of 21199999 is 99999112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21199999 - 2⁹ = 21199487 is a prime.

21199999 is a modest number, since divided by 9999 gives 2119 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21199909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10599999 + 10600000.

It is an arithmetic number, because the mean of its divisors is an integer number (10600000).

Almost surely, 2^21199999 is an apocalyptic number.

21199999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21199999 is an equidigital number, since it uses as much as digits as its factorization.

21199999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 118098, while the sum is 49.

The square root of 21199999 is about 4604.3456646955. The cubic root of 21199999 is about 276.7654963772.

The spelling of 21199999 in words is "twenty-one million, one hundred ninety-nine thousand, nine hundred ninety-nine".