1257209861 has 2 divisors, whose sum is σ = 1257209862. Its totient is φ = 1257209860.

The previous prime is 1257209813. The next prime is 1257209887. The reversal of 1257209861 is 1689027521.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1244748961 + 12460900 = 35281^2 + 3530^2 .

It is a cyclic number.

It is not a de Polignac number, because 1257209861 - 2⁶ = 1257209797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1257209561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628604930 + 628604931.

It is an arithmetic number, because the mean of its divisors is an integer number (628604931).

Almost surely, 2^1257209861 is an apocalyptic number.

It is an amenable number.

1257209861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1257209861 is an equidigital number, since it uses as much as digits as its factorization.

1257209861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60480, while the sum is 41.

The square root of 1257209861 is about 35457.1552863452. The cubic root of 1257209861 is about 1079.2844657411.

The spelling of 1257209861 in words is "one billion, two hundred fifty-seven million, two hundred nine thousand, eight hundred sixty-one".