251506 has 4 divisors (see below), whose sum is σ = 377262. Its totient is φ = 125752.

The previous prime is 251501. The next prime is 251513. The reversal of 251506 is 605152.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 156025 + 95481 = 395^2 + 309^2 .

It is not an unprimeable number, because it can be changed into a prime (251501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 62875 + ... + 62878.

2²⁵¹⁵⁰⁶ is an apocalyptic number.

251506 is a deficient number, since it is larger than the sum of its proper divisors (125756).

251506 is a wasteful number, since it uses less digits than its factorization.

251506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125755.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 251506 is about 501.5037387697. The cubic root of 251506 is about 63.1222954107.

Adding to 251506 its reverse (605152), we get a palindrome (856658).

It can be divided in two parts, 251 and 506, that added together give a palindrome (757).

The spelling of 251506 in words is "two hundred fifty-one thousand, five hundred six".