1981931 has 4 divisors (see below), whose sum is σ = 2265072. Its totient is φ = 1698792.

The previous prime is 1981921. The next prime is 1981939. The reversal of 1981931 is 1391891.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1981931 - 2⁶ = 1981867 is a prime.

It is a super-2 number, since 2×1981931² = 7856100977522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1981939) 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, 141560 + ... + 141573.

It is an arithmetic number, because the mean of its divisors is an integer number (566268).

2^1981931 is an apocalyptic number.

1981931 is a deficient number, since it is larger than the sum of its proper divisors (283141).

1981931 is an equidigital number, since it uses as much as digits as its factorization.

1981931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283140.

The product of its digits is 1944, while the sum is 32.

The square root of 1981931 is about 1407.8107117081. The cubic root of 1981931 is about 125.6115313564.

The spelling of 1981931 in words is "one million, nine hundred eighty-one thousand, nine hundred thirty-one".