19881000961 has 4 divisors (see below), whose sum is σ = 19911447252. Its totient is φ = 19850554672.

The previous prime is 19881000959. The next prime is 19881001037. The reversal of 19881000961 is 16900018891.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16900018891 = 7 ⋅2414288413.

It can be written as a sum of positive squares in 2 ways, for example, as 4629985936 + 15251015025 = 68044^2 + 123495^2 .

It is a cyclic number.

It is not a de Polignac number, because 19881000961 - 2¹ = 19881000959 is a prime.

It is a super-2 number, since 2×19881000961² (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 (19881001961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15222166 + ... + 15223471.

It is an arithmetic number, because the mean of its divisors is an integer number (4977861813).

It is a Proth number, since it is equal to 1185 ⋅ 2²⁴ + 1 and 1185 < 2²⁴.

Almost surely, 2^19881000961 is an apocalyptic number.

It is an amenable number.

19881000961 is a deficient number, since it is larger than the sum of its proper divisors (30446291).

19881000961 is an equidigital number, since it uses as much as digits as its factorization.

19881000961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30446290.

The product of its (nonzero) digits is 31104, while the sum is 43.

The spelling of 19881000961 in words is "nineteen billion, eight hundred eighty-one million, nine hundred sixty-one", and thus it is an aban number.