1251588661 has 2 divisors, whose sum is σ = 1251588662. Its totient is φ = 1251588660.

The previous prime is 1251588647. The next prime is 1251588697. The reversal of 1251588661 is 1668851521.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1114558225 + 137030436 = 33385^2 + 11706^2 .

It is a cyclic number.

It is not a de Polignac number, because 1251588661 - 2⁵ = 1251588629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1251588361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 625794330 + 625794331.

It is an arithmetic number, because the mean of its divisors is an integer number (625794331).

Almost surely, 2^1251588661 is an apocalyptic number.

It is an amenable number.

1251588661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1251588661 is an equidigital number, since it uses as much as digits as its factorization.

1251588661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 115200, while the sum is 43.

The square root of 1251588661 is about 35377.7989846740. The cubic root of 1251588661 is about 1077.6735073364.

The spelling of 1251588661 in words is "one billion, two hundred fifty-one million, five hundred eighty-eight thousand, six hundred sixty-one".