1957991 has 12 divisors (see below), whose sum is σ = 2352960. Its totient is φ = 1622880.

The previous prime is 1957981. The next prime is 1957997. The reversal of 1957991 is 1997591.

It is a happy number.

It is not a de Polignac number, because 1957991 - 2¹⁴ = 1941607 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1957997) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 875 + ... + 2163.

It is an arithmetic number, because the mean of its divisors is an integer number (196080).

2^1957991 is an apocalyptic number.

1957991 is a deficient number, since it is larger than the sum of its proper divisors (394969).

1957991 is a wasteful number, since it uses less digits than its factorization.

1957991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1334 (or 1327 counting only the distinct ones).

The product of its digits is 25515, while the sum is 41.

The square root of 1957991 is about 1399.2823160463. The cubic root of 1957991 is about 125.1037219103.

The spelling of 1957991 in words is "one million, nine hundred fifty-seven thousand, nine hundred ninety-one".