1257131509 has 2 divisors, whose sum is σ = 1257131510. Its totient is φ = 1257131508.

The previous prime is 1257131507. The next prime is 1257131549. The reversal of 1257131509 is 9051317521.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 687593284 + 569538225 = 26222^2 + 23865^2 .

It is an emirp because it is prime and its reverse (9051317521) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1257131509 - 2¹ = 1257131507 is a prime.

Together with 1257131507, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1257131501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628565754 + 628565755.

It is an arithmetic number, because the mean of its divisors is an integer number (628565755).

Almost surely, 2^1257131509 is an apocalyptic number.

It is an amenable number.

1257131509 is a deficient number, since it is larger than the sum of its proper divisors (1).

1257131509 is an equidigital number, since it uses as much as digits as its factorization.

1257131509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9450, while the sum is 34.

The square root of 1257131509 is about 35456.0503863586. The cubic root of 1257131509 is about 1079.2620441720.

The spelling of 1257131509 in words is "one billion, two hundred fifty-seven million, one hundred thirty-one thousand, five hundred nine".