21947991833 has 4 divisors (see below), whose sum is σ = 22153113360. Its totient is φ = 21742870308.

The previous prime is 21947991823. The next prime is 21947991883. The reversal of 21947991833 is 33819974912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21947991833 - 2⁸ = 21947991577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21947991823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 102560603 + ... + 102560816.

It is an arithmetic number, because the mean of its divisors is an integer number (5538278340).

Almost surely, 2^21947991833 is an apocalyptic number.

It is an amenable number.

21947991833 is a deficient number, since it is larger than the sum of its proper divisors (205121527).

21947991833 is a wasteful number, since it uses less digits than its factorization.

21947991833 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205121526.

The product of its digits is 2939328, while the sum is 56.

The spelling of 21947991833 in words is "twenty-one billion, nine hundred forty-seven million, nine hundred ninety-one thousand, eight hundred thirty-three".