21163967999 has 4 divisors (see below), whose sum is σ = 21171394200. Its totient is φ = 21156541800.

The previous prime is 21163967927. The next prime is 21163968013. The reversal of 21163967999 is 99976936112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21163967999 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 (21163961999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3708824 + ... + 3714525.

It is an arithmetic number, because the mean of its divisors is an integer number (5292848550).

Almost surely, 2^21163967999 is an apocalyptic number.

21163967999 is a deficient number, since it is larger than the sum of its proper divisors (7426201).

21163967999 is an equidigital number, since it uses as much as digits as its factorization.

21163967999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7426200.

The product of its digits is 9920232, while the sum is 62.

The spelling of 21163967999 in words is "twenty-one billion, one hundred sixty-three million, nine hundred sixty-seven thousand, nine hundred ninety-nine".