21964336991 has 4 divisors (see below), whose sum is σ = 23256356832. Its totient is φ = 20672317152.

The previous prime is 21964336981. The next prime is 21964336997. The reversal of 21964336991 is 19963346912.

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

It is not a de Polignac number, because 21964336991 - 2²⁶ = 21897228127 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 (21964336997) 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, 646009895 + ... + 646009928.

It is an arithmetic number, because the mean of its divisors is an integer number (5814089208).

Almost surely, 2^21964336991 is an apocalyptic number.

21964336991 is a deficient number, since it is larger than the sum of its proper divisors (1292019841).

21964336991 is a wasteful number, since it uses less digits than its factorization.

21964336991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1292019840.

The product of its digits is 1889568, while the sum is 53.

The spelling of 21964336991 in words is "twenty-one billion, nine hundred sixty-four million, three hundred thirty-six thousand, nine hundred ninety-one".