1251 has 6 divisors (see below), whose sum is σ = 1820. Its totient is φ = 828.

The previous prime is 1249. The next prime is 1259. The reversal of 1251 is 1521.

It is a happy number.

1251 is an esthetic number in base 8, because in such base its adjacent digits differ by 1.

It is not a de Polignac number, because 1251 - 2¹ = 1249 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 139 = 1251 / (1 + 2 + 5 + 1).

It is a Duffinian number.

1251 is a lucky number.

It is a nialpdrome in base 6, base 12, base 13 and base 14.

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 5 ways as a sum of consecutive naturals, for example, 61 + ... + 78.

1251 is a deficient number, since it is larger than the sum of its proper divisors (569).

1251 is a wasteful number, since it uses less digits than its factorization.

1251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145 (or 142 counting only the distinct ones).

The product of its digits is 10, while the sum is 9.

The square root of 1251 is about 35.3694783677. The cubic root of 1251 is about 10.7750452641.

Adding to 1251 its reverse (1521), we get a palindrome (2772).

It can be divided in two parts, 1 and 251, that added together give a palindrome (252).

The spelling of 1251 in words is "one thousand, two hundred fifty-one".