20999761564807 has 2 divisors, whose sum is σ = 20999761564808. Its totient is φ = 20999761564806.

The previous prime is 20999761564777. The next prime is 20999761564853. The reversal of 20999761564807 is 70846516799902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20999761564807 - 2¹⁵ = 20999761532039 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20999761564807.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20999761564207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10499880782403 + 10499880782404.

It is an arithmetic number, because the mean of its divisors is an integer number (10499880782404).

Almost surely, 2^{20999761564807} is an apocalyptic number.

20999761564807 is a deficient number, since it is larger than the sum of its proper divisors (1).

20999761564807 is an equidigital number, since it uses as much as digits as its factorization.

20999761564807 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 411505920, while the sum is 73.

The spelling of 20999761564807 in words is "twenty trillion, nine hundred ninety-nine billion, seven hundred sixty-one million, five hundred sixty-four thousand, eight hundred seven".