1981957 has 4 divisors (see below), whose sum is σ = 2005920. Its totient is φ = 1957996.

The previous prime is 1981949. The next prime is 1981963. The reversal of 1981957 is 7591891.

It is a happy number.

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: 7591891 = 1889 ⋅4019.

It is a cyclic number.

It is not a de Polignac number, because 1981957 - 2³ = 1981949 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11857 + ... + 12022.

It is an arithmetic number, because the mean of its divisors is an integer number (501480).

2^1981957 is an apocalyptic number.

It is an amenable number.

1981957 is a deficient number, since it is larger than the sum of its proper divisors (23963).

1981957 is an equidigital number, since it uses as much as digits as its factorization.

1981957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23962.

The product of its digits is 22680, while the sum is 40.

The square root of 1981957 is about 1407.8199458738. The cubic root of 1981957 is about 125.6120806331.

The spelling of 1981957 in words is "one million, nine hundred eighty-one thousand, nine hundred fifty-seven".