21704567761 has 2 divisors, whose sum is σ = 21704567762. Its totient is φ = 21704567760.

The previous prime is 21704567737. The next prime is 21704567821. The reversal of 21704567761 is 16776540712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16960113361 + 4744454400 = 130231^2 + 68880^2 .

It is a cyclic number.

It is not a de Polignac number, because 21704567761 - 2²¹ = 21702470609 is a prime.

It is not a weakly prime, because it can be changed into another prime (21704577761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10852283880 + 10852283881.

It is an arithmetic number, because the mean of its divisors is an integer number (10852283881).

Almost surely, 2^21704567761 is an apocalyptic number.

It is an amenable number.

21704567761 is a deficient number, since it is larger than the sum of its proper divisors (1).

21704567761 is an equidigital number, since it uses as much as digits as its factorization.

21704567761 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 493920, while the sum is 46.

The spelling of 21704567761 in words is "twenty-one billion, seven hundred four million, five hundred sixty-seven thousand, seven hundred sixty-one".