1994113981 has 4 divisors (see below), whose sum is σ = 1994218492. Its totient is φ = 1994009472.

The previous prime is 1994113939. The next prime is 1994114009. The reversal of 1994113981 is 1893114991.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1893114991 = 26459 ⋅71549.

It can be written as a sum of positive squares in 2 ways, for example, as 1241434756 + 752679225 = 35234^2 + 27435^2 .

It is a cyclic number.

It is not a de Polignac number, because 1994113981 - 2¹⁷ = 1993982909 is a prime.

It is a super-2 number, since 2×1994113981² = 7952981138439336722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1994113081) 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, 14580 + ... + 64813.

It is an arithmetic number, because the mean of its divisors is an integer number (498554623).

Almost surely, 2^1994113981 is an apocalyptic number.

It is an amenable number.

1994113981 is a deficient number, since it is larger than the sum of its proper divisors (104511).

1994113981 is an equidigital number, since it uses as much as digits as its factorization.

1994113981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104510.

The product of its digits is 69984, while the sum is 46.

The square root of 1994113981 is about 44655.5033674462. The cubic root of 1994113981 is about 1258.6838488621.

The spelling of 1994113981 in words is "one billion, nine hundred ninety-four million, one hundred thirteen thousand, nine hundred eighty-one".