21765342671 has 2 divisors, whose sum is σ = 21765342672. Its totient is φ = 21765342670.

The previous prime is 21765342649. The next prime is 21765342749. The reversal of 21765342671 is 17624356712.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21765342671 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21765642671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882671335 + 10882671336.

It is an arithmetic number, because the mean of its divisors is an integer number (10882671336).

Almost surely, 2^21765342671 is an apocalyptic number.

21765342671 is a deficient number, since it is larger than the sum of its proper divisors (1).

21765342671 is an equidigital number, since it uses as much as digits as its factorization.

21765342671 is an evil number, because the sum of its binary digits is even.

The product of its digits is 423360, while the sum is 44.

The spelling of 21765342671 in words is "twenty-one billion, seven hundred sixty-five million, three hundred forty-two thousand, six hundred seventy-one".