21390007799 has 2 divisors, whose sum is σ = 21390007800. Its totient is φ = 21390007798.

The previous prime is 21390007759. The next prime is 21390007811. The reversal of 21390007799 is 99770009312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21390007799 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21390007759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10695003899 + 10695003900.

It is an arithmetic number, because the mean of its divisors is an integer number (10695003900).

Almost surely, 2^21390007799 is an apocalyptic number.

21390007799 is a deficient number, since it is larger than the sum of its proper divisors (1).

21390007799 is an equidigital number, since it uses as much as digits as its factorization.

21390007799 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 214326, while the sum is 47.

The spelling of 21390007799 in words is "twenty-one billion, three hundred ninety million, seven thousand, seven hundred ninety-nine".