1291625604 has 18 divisors (see below), whose sum is σ = 3264942590. Its totient is φ = 430541856.

The previous prime is 1291625597. The next prime is 1291625623. The reversal of 1291625604 is 4065261921.

1291625604 is a `hidden beast` number, since 1 + 2 + 91 + 6 + 2 + 560 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1156136004 + 135489600 = 34002^2 + 11640^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 35878489 = 1291625604 / (1 + 2 + 9 + 1 + 6 + 2 + 5 + 6 + 0 + 4).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17939209 + ... + 17939280.

Almost surely, 2^1291625604 is an apocalyptic number.

It is an amenable number.

1291625604 is an abundant number, since it is smaller than the sum of its proper divisors (1973316986).

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

1291625604 is a wasteful number, since it uses less digits than its factorization.

1291625604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35878499 (or 35878494 counting only the distinct ones).

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

The square root of 1291625604 is about 35939.1931462018. The cubic root of 1291625604 is about 1089.0443055332.

The spelling of 1291625604 in words is "one billion, two hundred ninety-one million, six hundred twenty-five thousand, six hundred four".