19561190681 has 4 divisors (see below), whose sum is σ = 20192196864. Its totient is φ = 18930184500.

The previous prime is 19561190653. The next prime is 19561190683. The reversal of 19561190681 is 18609116591.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 19561190681 - 2¹⁸ = 19560928537 is a prime.

It is a super-2 number, since 2×19561190681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19561190683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 315503045 + ... + 315503106.

It is an arithmetic number, because the mean of its divisors is an integer number (5048049216).

Almost surely, 2^19561190681 is an apocalyptic number.

It is an amenable number.

19561190681 is a deficient number, since it is larger than the sum of its proper divisors (631006183).

19561190681 is an equidigital number, since it uses as much as digits as its factorization.

19561190681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 631006182.

The product of its (nonzero) digits is 116640, while the sum is 47.

The spelling of 19561190681 in words is "nineteen billion, five hundred sixty-one million, one hundred ninety thousand, six hundred eighty-one".