251606 has 4 divisors (see below), whose sum is σ = 377412. Its totient is φ = 125802.

The previous prime is 251567. The next prime is 251609. The reversal of 251606 is 606152.

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

It is a Curzon number.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251609) by changing a digit.

251606 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 62900 + ... + 62903.

It is an arithmetic number, because the mean of its divisors is an integer number (94353).

2²⁵¹⁶⁰⁶ is an apocalyptic number.

251606 is a deficient number, since it is larger than the sum of its proper divisors (125806).

251606 is a wasteful number, since it uses less digits than its factorization.

251606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125805.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 251606 is about 501.6034290154. The cubic root of 251606 is about 63.1306602120.

Adding to 251606 its reverse (606152), we get a palindrome (857758).

The spelling of 251606 in words is "two hundred fifty-one thousand, six hundred six".