19561981241 has 4 divisors (see below), whose sum is σ = 21340343184. Its totient is φ = 17783619300.

The previous prime is 19561981217. The next prime is 19561981261. The reversal of 19561981241 is 14218916591.

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 a de Polignac number, because none of the positive numbers 2^k-19561981241 is a prime.

It is a super-2 number, since 2×19561981241² (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 (19561981211) 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, 889180955 + ... + 889180976.

It is an arithmetic number, because the mean of its divisors is an integer number (5335085796).

Almost surely, 2^19561981241 is an apocalyptic number.

19561981241 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

19561981241 is a deficient number, since it is larger than the sum of its proper divisors (1778361943).

19561981241 is a wasteful number, since it uses less digits than its factorization.

19561981241 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1778361942.

The product of its digits is 155520, while the sum is 47.

The spelling of 19561981241 in words is "nineteen billion, five hundred sixty-one million, nine hundred eighty-one thousand, two hundred forty-one".