1291788 has 42 divisors (see below), whose sum is σ = 3397044. Its totient is φ = 429624.

The previous prime is 1291783. The next prime is 1291793. The reversal of 1291788 is 8871921.

It is an interprime number because it is at equal distance from previous prime (1291783) and next prime (1291793).

It is a Harshad number since it is a multiple of its sum of digits (36).

Its product of digits (8064) is a multiple of the sum of its prime divisors (448).

It is not an unprimeable number, because it can be changed into a prime (1291783) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 2695 + ... + 3137.

It is an arithmetic number, because the mean of its divisors is an integer number (80882).

2^1291788 is an apocalyptic number.

1291788 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1291788, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1698522).

1291788 is an abundant number, since it is smaller than the sum of its proper divisors (2105256).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1291788 is an equidigital number, since it uses as much as digits as its factorization.

1291788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 465 (or 448 counting only the distinct ones).

The product of its digits is 8064, while the sum is 36.

The square root of 1291788 is about 1136.5685197119. The cubic root of 1291788 is about 108.9089945443.

The spelling of 1291788 in words is "one million, two hundred ninety-one thousand, seven hundred eighty-eight".