19647774661 has 2 divisors, whose sum is σ = 19647774662. Its totient is φ = 19647774660.

The previous prime is 19647774631. The next prime is 19647774761. The reversal of 19647774661 is 16647774691.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17910468900 + 1737305761 = 133830^2 + 41681^2 .

It is an emirp because it is prime and its reverse (16647774691) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19647774661 - 2²⁵ = 19614220229 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 19647774596 and 19647774605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19647774631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9823887330 + 9823887331.

It is an arithmetic number, because the mean of its divisors is an integer number (9823887331).

Almost surely, 2^19647774661 is an apocalyptic number.

It is an amenable number.

19647774661 is a deficient number, since it is larger than the sum of its proper divisors (1).

19647774661 is an equidigital number, since it uses as much as digits as its factorization.

19647774661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10668672, while the sum is 58.

The spelling of 19647774661 in words is "nineteen billion, six hundred forty-seven million, seven hundred seventy-four thousand, six hundred sixty-one".