21640268754191 has 2 divisors, whose sum is σ = 21640268754192. Its totient is φ = 21640268754190.

The previous prime is 21640268754151. The next prime is 21640268754259. The reversal of 21640268754191 is 19145786204612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21640268754191 - 2³⁴ = 21623088885007 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21640268754121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10820134377095 + 10820134377096.

It is an arithmetic number, because the mean of its divisors is an integer number (10820134377096).

Almost surely, 2^{21640268754191} is an apocalyptic number.

21640268754191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21640268754191 is an equidigital number, since it uses as much as digits as its factorization.

21640268754191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5806080, while the sum is 56.

The spelling of 21640268754191 in words is "twenty-one trillion, six hundred forty billion, two hundred sixty-eight million, seven hundred fifty-four thousand, one hundred ninety-one".