1257 has 4 divisors (see below), whose sum is σ = 1680. Its totient is φ = 836.

The previous prime is 1249. The next prime is 1259. The reversal of 1257 is 7521.

Added to its reverse (7521) it gives a triangular number (8778 = T_{132}).

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1257 - 2^{3} = 1249 is a prime.

It is an Ulam number.

It is a D-number.

It is a plaindrome in base 7, base 10, base 12 and base 15.

It is a nialpdrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (1259) 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, 207 + ... + 212.

It is an arithmetic number, because the mean of its divisors is an integer number (420).

2^{1257} is an apocalyptic number.

It is an amenable number.

1257 is a deficient number, since it is larger than the sum of its proper divisors (423).

1257 is an equidigital number, since it uses as much as digits as its factorization.

1257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422.

The product of its digits is 70, while the sum is 15.

The square root of 1257 is about 35.4541958025. The cubic root of 1257 is about 10.7922440886.

Multiplying 1257 by its product of digits (70), we get a triangular number (87990 = T_{419}).

Adding to 1257 its reverse (7521), we get a palindrome (8778).

The spelling of 1257 in words is "one thousand, two hundred fifty-seven".

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