21445767437491 has 2 divisors, whose sum is σ = 21445767437492. Its totient is φ = 21445767437490.

The previous prime is 21445767437483. The next prime is 21445767437503. The reversal of 21445767437491 is 19473476754412.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21445767437491 - 2³ = 21445767437483 is a prime.

It is not a weakly prime, because it can be changed into another prime (21445767137491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10722883718745 + 10722883718746.

It is an arithmetic number, because the mean of its divisors is an integer number (10722883718746).

Almost surely, 2^{21445767437491} is an apocalyptic number.

21445767437491 is a deficient number, since it is larger than the sum of its proper divisors (1).

21445767437491 is an equidigital number, since it uses as much as digits as its factorization.

21445767437491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 142248960, while the sum is 64.

The spelling of 21445767437491 in words is "twenty-one trillion, four hundred forty-five billion, seven hundred sixty-seven million, four hundred thirty-seven thousand, four hundred ninety-one".