1257342781 has 2 divisors, whose sum is σ = 1257342782. Its totient is φ = 1257342780.

The previous prime is 1257342743. The next prime is 1257342787. The reversal of 1257342781 is 1872437521.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1232641881 + 24700900 = 35109^2 + 4970^2 .

It is a cyclic number.

It is not a de Polignac number, because 1257342781 - 2⁹ = 1257342269 is a prime.

It is a super-2 number, since 2×1257342781² = 3161821737865627922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1257342787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628671390 + 628671391.

It is an arithmetic number, because the mean of its divisors is an integer number (628671391).

Almost surely, 2^1257342781 is an apocalyptic number.

It is an amenable number.

1257342781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1257342781 is an equidigital number, since it uses as much as digits as its factorization.

1257342781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 94080, while the sum is 40.

The square root of 1257342781 is about 35459.0296116518. The cubic root of 1257342781 is about 1079.3225006097.

The spelling of 1257342781 in words is "one billion, two hundred fifty-seven million, three hundred forty-two thousand, seven hundred eighty-one".