1291625640 has 96 divisors (see below), whose sum is σ = 4269002400. Its totient is φ = 338590080.

The previous prime is 1291625623. The next prime is 1291625663. The reversal of 1291625640 is 465261921.

1291625640 = T₃₉₁ + T₃₉₂ + ... + T₁₉₈₃.

1291625640 is a `hidden beast` number, since 1 + 2 + 9 + 1 + 6 + 2 + 5 + 640 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 1291625595 and 1291625604.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9166 + ... + 51645.

It is an arithmetic number, because the mean of its divisors is an integer number (44468775).

Almost surely, 2^1291625640 is an apocalyptic number.

1291625640 is a gapful number since it is divisible by the number (10) 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 1291625640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2134501200).

1291625640 is an abundant number, since it is smaller than the sum of its proper divisors (2977376760).

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

1291625640 is a wasteful number, since it uses less digits than its factorization.

1291625640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60887 (or 60880 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 1291625640 is about 35939.1936470478. The cubic root of 1291625640 is about 1089.0443156511.

The spelling of 1291625640 in words is "one billion, two hundred ninety-one million, six hundred twenty-five thousand, six hundred forty".