21118406399 has 2 divisors, whose sum is σ = 21118406400. Its totient is φ = 21118406398.

The previous prime is 21118406389. The next prime is 21118406453. The reversal of 21118406399 is 99360481112.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21118406399 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21118406389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10559203199 + 10559203200.

It is an arithmetic number, because the mean of its divisors is an integer number (10559203200).

Almost surely, 2^21118406399 is an apocalyptic number.

21118406399 is a deficient number, since it is larger than the sum of its proper divisors (1).

21118406399 is an equidigital number, since it uses as much as digits as its factorization.

21118406399 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 93312, while the sum is 44.

The spelling of 21118406399 in words is "twenty-one billion, one hundred eighteen million, four hundred six thousand, three hundred ninety-nine".