1291631 has 8 divisors (see below), whose sum is σ = 1458000. Its totient is φ = 1133440.

The previous prime is 1291603. The next prime is 1291637. The reversal of 1291631 is 1361921.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1291631 - 2⁶ = 1291567 is a prime.

It is a super-2 number, since 2×1291631² = 3336621280322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1291597 and 1291606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1291637) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1706 + ... + 2343.

It is an arithmetic number, because the mean of its divisors is an integer number (182250).

2^1291631 is an apocalyptic number.

1291631 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1291631 is a deficient number, since it is larger than the sum of its proper divisors (166369).

1291631 is a wasteful number, since it uses less digits than its factorization.

1291631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4089.

The product of its digits is 324, while the sum is 23.

The square root of 1291631 is about 1136.4994500659. The cubic root of 1291631 is about 108.9045822091.

The spelling of 1291631 in words is "one million, two hundred ninety-one thousand, six hundred thirty-one".