21771374791 has 2 divisors, whose sum is σ = 21771374792. Its totient is φ = 21771374790.

The previous prime is 21771374777. The next prime is 21771374837. The reversal of 21771374791 is 19747317712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21771374791 - 2⁵ = 21771374759 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21771374731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885687395 + 10885687396.

It is an arithmetic number, because the mean of its divisors is an integer number (10885687396).

Almost surely, 2^21771374791 is an apocalyptic number.

21771374791 is a deficient number, since it is larger than the sum of its proper divisors (1).

21771374791 is an equidigital number, since it uses as much as digits as its factorization.

21771374791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 518616, while the sum is 49.

The spelling of 21771374791 in words is "twenty-one billion, seven hundred seventy-one million, three hundred seventy-four thousand, seven hundred ninety-one".