1257391 has 8 divisors (see below), whose sum is σ = 1327104. Its totient is φ = 1189560.

The previous prime is 1257359. The next prime is 1257397. The reversal of 1257391 is 1937521.

1257391 = 140² + 141² + ... + 186².

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1257391 - 2⁵ = 1257359 is a prime.

It is a Duffinian number.

1257391 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1257397) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1026 + ... + 1888.

It is an arithmetic number, because the mean of its divisors is an integer number (165888).

2^1257391 is an apocalyptic number.

1257391 is a deficient number, since it is larger than the sum of its proper divisors (69713).

1257391 is an equidigital number, since it uses as much as digits as its factorization.

1257391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 941.

The product of its digits is 1890, while the sum is 28.

The square root of 1257391 is about 1121.3344728492. The cubic root of 1257391 is about 107.9336297745.

The spelling of 1257391 in words is "one million, two hundred fifty-seven thousand, three hundred ninety-one".