21264444191 has 2 divisors, whose sum is σ = 21264444192. Its totient is φ = 21264444190.

The previous prime is 21264444143. The next prime is 21264444199. The reversal of 21264444191 is 19144446212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21264444191 - 2³⁴ = 4084575007 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21264444199) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10632222095 + 10632222096.

It is an arithmetic number, because the mean of its divisors is an integer number (10632222096).

Almost surely, 2^21264444191 is an apocalyptic number.

21264444191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21264444191 is an equidigital number, since it uses as much as digits as its factorization.

21264444191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55296, while the sum is 38.

The spelling of 21264444191 in words is "twenty-one billion, two hundred sixty-four million, four hundred forty-four thousand, one hundred ninety-one".