1491391 has 4 divisors (see below), whose sum is σ = 1626984. Its totient is φ = 1355800.

The previous prime is 1491377. The next prime is 1491401. The reversal of 1491391 is 1931941.

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: 1931941 = 11 ⋅175631.

It is a cyclic number.

It is not a de Polignac number, because 1491391 - 2¹⁵ = 1458623 is a prime.

It is a super-2 number, since 2×1491391² = 4448494229762, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1491491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67780 + ... + 67801.

It is an arithmetic number, because the mean of its divisors is an integer number (406746).

2^1491391 is an apocalyptic number.

1491391 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1491391 is a deficient number, since it is larger than the sum of its proper divisors (135593).

1491391 is a wasteful number, since it uses less digits than its factorization.

1491391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135592.

The product of its digits is 972, while the sum is 28.

The square root of 1491391 is about 1221.2252044566. The cubic root of 1491391 is about 114.2520073959.

It can be divided in two parts, 149 and 1391, that added together give a triangular number (1540 = T₅₅).

The spelling of 1491391 in words is "one million, four hundred ninety-one thousand, three hundred ninety-one".