1291728 has 40 divisors (see below), whose sum is σ = 3535488. Its totient is φ = 404992.

The previous prime is 1291691. The next prime is 1291783. The reversal of 1291728 is 8271921.

It is a super-2 number, since 2×1291728² = 3337122451968, which contains 22 as substring.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 1291695 and 1291704.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25 + ... + 1607.

2^1291728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1291728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1767744).

1291728 is an abundant number, since it is smaller than the sum of its proper divisors (2243760).

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

1291728 is a wasteful number, since it uses less digits than its factorization.

1291728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1611 (or 1605 counting only the distinct ones).

The product of its digits is 2016, while the sum is 30.

The square root of 1291728 is about 1136.5421241643. The cubic root of 1291728 is about 108.9073083438.

The spelling of 1291728 in words is "one million, two hundred ninety-one thousand, seven hundred twenty-eight".