1597991 has 4 divisors (see below), whose sum is σ = 1602000. Its totient is φ = 1593984.

The previous prime is 1597979. The next prime is 1598011. The reversal of 1597991 is 1997951.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1997951 = 1051 ⋅1901.

It is a cyclic number.

It is not a de Polignac number, because 1597991 - 2⁶ = 1597927 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 (1597931) 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, 1331 + ... + 2228.

It is an arithmetic number, because the mean of its divisors is an integer number (400500).

2^1597991 is an apocalyptic number.

1597991 is a deficient number, since it is larger than the sum of its proper divisors (4009).

1597991 is an equidigital number, since it uses as much as digits as its factorization.

1597991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4008.

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

The square root of 1597991 is about 1264.1166876519. The cubic root of 1597991 is about 116.9117360951.

The spelling of 1597991 in words is "one million, five hundred ninety-seven thousand, nine hundred ninety-one".