1290139685 has 4 divisors (see below), whose sum is σ = 1548167628. Its totient is φ = 1032111744.

The previous prime is 1290139657. The next prime is 1290139687. The reversal of 1290139685 is 5869310921.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 235254244 + 1054885441 = 15338^2 + 32479^2 .

It is a cyclic number.

It is not a de Polignac number, because 1290139685 - 2⁸ = 1290139429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1290139687) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 129013964 + ... + 129013973.

It is an arithmetic number, because the mean of its divisors is an integer number (387041907).

Almost surely, 2^1290139685 is an apocalyptic number.

It is an amenable number.

1290139685 is a deficient number, since it is larger than the sum of its proper divisors (258027943).

1290139685 is an equidigital number, since it uses as much as digits as its factorization.

1290139685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258027942.

The product of its (nonzero) digits is 116640, while the sum is 44.

The square root of 1290139685 is about 35918.5145154974. The cubic root of 1290139685 is about 1088.6265238456.

The spelling of 1290139685 in words is "one billion, two hundred ninety million, one hundred thirty-nine thousand, six hundred eighty-five".