251801 has 6 divisors (see below), whose sum is σ = 276906. Its totient is φ = 228800.

The previous prime is 251791. The next prime is 251809. The reversal of 251801 is 108152.

It can be written as a sum of positive squares in only one way, i.e., 203401 + 48400 = 451^2 + 220^2 .

It is not a de Polignac number, because 251801 - 2⁶ = 251737 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 251801.

It is not an unprimeable number, because it can be changed into a prime (251809) 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, 920 + ... + 1161.

It is an arithmetic number, because the mean of its divisors is an integer number (46151).

2²⁵¹⁸⁰¹ is an apocalyptic number.

It is an amenable number.

251801 is a deficient number, since it is larger than the sum of its proper divisors (25105).

251801 is a wasteful number, since it uses less digits than its factorization.

251801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2103 (or 2092 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 17.

The square root of 251801 is about 501.7977680301. The cubic root of 251801 is about 63.1469652018.

Adding to 251801 its reverse (108152), we get a palindrome (359953).

The spelling of 251801 in words is "two hundred fifty-one thousand, eight hundred one".