1257221761 has 2 divisors, whose sum is σ = 1257221762. Its totient is φ = 1257221760.

The previous prime is 1257221747. The next prime is 1257221821. The reversal of 1257221761 is 1671227521.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 811167361 + 446054400 = 28481^2 + 21120^2 .

It is a cyclic number.

It is not a de Polignac number, because 1257221761 - 2¹⁷ = 1257090689 is a prime.

It is a super-2 number, since 2×1257221761² = 3161213112663882242, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1257221711) 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, 628610880 + 628610881.

It is an arithmetic number, because the mean of its divisors is an integer number (628610881).

Almost surely, 2^1257221761 is an apocalyptic number.

It is an amenable number.

1257221761 is a deficient number, since it is larger than the sum of its proper divisors (1).

1257221761 is an equidigital number, since it uses as much as digits as its factorization.

1257221761 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11760, while the sum is 34.

The square root of 1257221761 is about 35457.3230941085. The cubic root of 1257221761 is about 1079.2878710184.

The spelling of 1257221761 in words is "one billion, two hundred fifty-seven million, two hundred twenty-one thousand, seven hundred sixty-one".