1257349981 has 2 divisors, whose sum is σ = 1257349982. Its totient is φ = 1257349980.

The previous prime is 1257349967. The next prime is 1257349991. The reversal of 1257349981 is 1899437521.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1199513956 + 57836025 = 34634^2 + 7605^2 .

It is an emirp because it is prime and its reverse (1899437521) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1257349981 - 2⁷ = 1257349853 is a prime.

It is a super-2 number, since 2×1257349981² = 3161857949441400722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1257349991) 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, 628674990 + 628674991.

It is an arithmetic number, because the mean of its divisors is an integer number (628674991).

Almost surely, 2^1257349981 is an apocalyptic number.

It is an amenable number.

1257349981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1257349981 is an equidigital number, since it uses as much as digits as its factorization.

1257349981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 544320, while the sum is 49.

The square root of 1257349981 is about 35459.1311371274. The cubic root of 1257349981 is about 1079.3245608029.

The spelling of 1257349981 in words is "one billion, two hundred fifty-seven million, three hundred forty-nine thousand, nine hundred eighty-one".