21999715999 has 6 divisors (see below), whose sum is σ = 22549383440. Its totient is φ = 21463135920.

The previous prime is 21999715987. The next prime is 21999716009. The reversal of 21999715999 is 99951799912.

It is a happy number.

It is not a de Polignac number, because 21999715999 - 2¹¹ = 21999713951 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21999715909) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6541959 + ... + 6545320.

Almost surely, 2^21999715999 is an apocalyptic number.

21999715999 is a deficient number, since it is larger than the sum of its proper divisors (549667441).

21999715999 is an equidigital number, since it uses as much as digits as its factorization.

21999715999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13087361 (or 13087320 counting only the distinct ones).

The product of its digits is 37200870, while the sum is 70.

The spelling of 21999715999 in words is "twenty-one billion, nine hundred ninety-nine million, seven hundred fifteen thousand, nine hundred ninety-nine".