21244966891 has 4 divisors (see below), whose sum is σ = 21311986032. Its totient is φ = 21177947752.

The previous prime is 21244966879. The next prime is 21244966909. The reversal of 21244966891 is 19866944212.

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

It is a cyclic number.

It is not a de Polignac number, because 21244966891 - 2⁵ = 21244966859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21244966801) 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, 33509095 + ... + 33509728.

It is an arithmetic number, because the mean of its divisors is an integer number (5327996508).

Almost surely, 2^21244966891 is an apocalyptic number.

21244966891 is a deficient number, since it is larger than the sum of its proper divisors (67019141).

21244966891 is an equidigital number, since it uses as much as digits as its factorization.

21244966891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67019140.

The product of its digits is 1492992, while the sum is 52.

The spelling of 21244966891 in words is "twenty-one billion, two hundred forty-four million, nine hundred sixty-six thousand, eight hundred ninety-one".