1257947657 has 4 divisors (see below), whose sum is σ = 1331944596. Its totient is φ = 1183950720.

The previous prime is 1257947641. The next prime is 1257947659. The reversal of 1257947657 is 7567497521.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 391881616 + 866066041 = 19796^2 + 29429^2 .

It is not a de Polignac number, because 1257947657 - 2⁴ = 1257947641 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1257947599 and 1257947608.

It is not an unprimeable number, because it can be changed into a prime (1257947659) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36998444 + ... + 36998477.

It is an arithmetic number, because the mean of its divisors is an integer number (332986149).

Almost surely, 2^1257947657 is an apocalyptic number.

1257947657 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

1257947657 is a deficient number, since it is larger than the sum of its proper divisors (73996939).

1257947657 is an equidigital number, since it uses as much as digits as its factorization.

1257947657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73996938.

The product of its digits is 3704400, while the sum is 53.

The square root of 1257947657 is about 35467.5578099198. The cubic root of 1257947657 is about 1079.4955511688.

The spelling of 1257947657 in words is "one billion, two hundred fifty-seven million, nine hundred forty-seven thousand, six hundred fifty-seven".