251842 has 4 divisors (see below), whose sum is σ = 377766. Its totient is φ = 125920.

The previous prime is 251833. The next prime is 251843. The reversal of 251842 is 248152.

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., 251001 + 841 = 501^2 + 29^2 .

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (251843) by changing a digit.

251842 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 62959 + ... + 62962.

2²⁵¹⁸⁴² is an apocalyptic number.

251842 is a deficient number, since it is larger than the sum of its proper divisors (125924).

251842 is a wasteful number, since it uses less digits than its factorization.

251842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125923.

The product of its digits is 640, while the sum is 22.

The square root of 251842 is about 501.8386194784. The cubic root of 251842 is about 63.1503923593.

Adding to 251842 its reverse (248152), we get a palindrome (499994).

It can be divided in two parts, 2 and 51842, that multiplied together give a square (103684 = 322²).

The spelling of 251842 in words is "two hundred fifty-one thousand, eight hundred forty-two".