21198911 has 2 divisors, whose sum is σ = 21198912. Its totient is φ = 21198910.

The previous prime is 21198907. The next prime is 21198917. The reversal of 21198911 is 11989112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21198911 - 2² = 21198907 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21198917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10599455 + 10599456.

It is an arithmetic number, because the mean of its divisors is an integer number (10599456).

Almost surely, 2^21198911 is an apocalyptic number.

21198911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21198911 is an equidigital number, since it uses as much as digits as its factorization.

21198911 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1296, while the sum is 32.

The square root of 21198911 is about 4604.2275139267. The cubic root of 21198911 is about 276.7607616913.

The spelling of 21198911 in words is "twenty-one million, one hundred ninety-eight thousand, nine hundred eleven".