1631391 has 4 divisors (see below), whose sum is σ = 2175192. Its totient is φ = 1087592.

The previous prime is 1631369. The next prime is 1631407. The reversal of 1631391 is 1931361.

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 1631391 - 2⁷ = 1631263 is a prime.

It is a super-2 number, since 2×1631391² = 5322873189762, which contains 22 as substring.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1631341) 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, 271896 + ... + 271901.

It is an arithmetic number, because the mean of its divisors is an integer number (543798).

2^1631391 is an apocalyptic number.

1631391 is a deficient number, since it is larger than the sum of its proper divisors (543801).

1631391 is an equidigital number, since it uses as much as digits as its factorization.

1631391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 543800.

The product of its digits is 486, while the sum is 24.

The square root of 1631391 is about 1277.2591749524. The cubic root of 1631391 is about 117.7206597441.

The spelling of 1631391 in words is "one million, six hundred thirty-one thousand, three hundred ninety-one".