1981779941 has 4 divisors (see below), whose sum is σ = 1981990272. Its totient is φ = 1981569612.

The previous prime is 1981779923. The next prime is 1981779953. The reversal of 1981779941 is 1499771891.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1499771891 = 2531 ⋅592561.

It is a cyclic number.

It is not a de Polignac number, because 1981779941 - 2¹⁰ = 1981778917 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981779991) 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, 90335 + ... + 110108.

It is an arithmetic number, because the mean of its divisors is an integer number (495497568).

Almost surely, 2^1981779941 is an apocalyptic number.

It is an amenable number.

1981779941 is a deficient number, since it is larger than the sum of its proper divisors (210331).

1981779941 is an equidigital number, since it uses as much as digits as its factorization.

1981779941 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210330.

The product of its digits is 1143072, while the sum is 56.

The square root of 1981779941 is about 44517.1870292812. The cubic root of 1981779941 is about 1256.0833998487.

The spelling of 1981779941 in words is "one billion, nine hundred eighty-one million, seven hundred seventy-nine thousand, nine hundred forty-one".