1981977923 has 2 divisors, whose sum is σ = 1981977924. Its totient is φ = 1981977922.

The previous prime is 1981977917. The next prime is 1981977937. The reversal of 1981977923 is 3297791891.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1981977923 - 2⁶ = 1981977859 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (1981977953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990988961 + 990988962.

It is an arithmetic number, because the mean of its divisors is an integer number (990988962).

Almost surely, 2^1981977923 is an apocalyptic number.

1981977923 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981977923 is an equidigital number, since it uses as much as digits as its factorization.

1981977923 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1714608, while the sum is 56.

The square root of 1981977923 is about 44519.4106317683. The cubic root of 1981977923 is about 1256.1252264945.

The spelling of 1981977923 in words is "one billion, nine hundred eighty-one million, nine hundred seventy-seven thousand, nine hundred twenty-three".