1291639 has 8 divisors (see below), whose sum is σ = 1371440. Its totient is φ = 1213056.

The previous prime is 1291637. The next prime is 1291669. The reversal of 1291639 is 9361921.

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

It is a cyclic number.

It is not a de Polignac number, because 1291639 - 2¹ = 1291637 is a prime.

It is a Duffinian number.

It is a plaindrome in base 14.

It is a self number, because there is not a number n which added to its sum of digits gives 1291639.

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, 2767 + ... + 3199.

It is an arithmetic number, because the mean of its divisors is an integer number (171430).

2^1291639 is an apocalyptic number.

1291639 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

1291639 is a deficient number, since it is larger than the sum of its proper divisors (79801).

1291639 is a wasteful number, since it uses less digits than its factorization.

1291639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 609.

The product of its digits is 2916, while the sum is 31.

The square root of 1291639 is about 1136.5029696398. The cubic root of 1291639 is about 108.9048070501.

The spelling of 1291639 in words is "one million, two hundred ninety-one thousand, six hundred thirty-nine".