21717066961 has 2 divisors, whose sum is σ = 21717066962. Its totient is φ = 21717066960.

The previous prime is 21717066913. The next prime is 21717067111. The reversal of 21717066961 is 16966071712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17644074561 + 4072992400 = 132831^2 + 63820^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21717066961 is a prime.

It is not a weakly prime, because it can be changed into another prime (21717066661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858533480 + 10858533481.

It is an arithmetic number, because the mean of its divisors is an integer number (10858533481).

Almost surely, 2^21717066961 is an apocalyptic number.

It is an amenable number.

21717066961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717066961 is an equidigital number, since it uses as much as digits as its factorization.

21717066961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 190512, while the sum is 46.

The spelling of 21717066961 in words is "twenty-one billion, seven hundred seventeen million, sixty-six thousand, nine hundred sixty-one".