21108326891 has 2 divisors, whose sum is σ = 21108326892. Its totient is φ = 21108326890.

The previous prime is 21108326873. The next prime is 21108326903. The reversal of 21108326891 is 19862380112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21108326891 - 2¹⁴ = 21108310507 is a prime.

It is a super-2 number, since 2×21108326891² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21108326851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10554163445 + 10554163446.

It is an arithmetic number, because the mean of its divisors is an integer number (10554163446).

Almost surely, 2^21108326891 is an apocalyptic number.

21108326891 is a deficient number, since it is larger than the sum of its proper divisors (1).

21108326891 is an equidigital number, since it uses as much as digits as its factorization.

21108326891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 41472, while the sum is 41.

The spelling of 21108326891 in words is "twenty-one billion, one hundred eight million, three hundred twenty-six thousand, eight hundred ninety-one".