251421 has 8 divisors (see below), whose sum is σ = 343200. Its totient is φ = 163632.

The previous prime is 251417. The next prime is 251429. The reversal of 251421 is 124152.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 251421 - 2² = 251417 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 251421.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 251421.

It is not an unprimeable number, because it can be changed into a prime (251429) 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 in 7 ways as a sum of consecutive naturals, for example, 846 + ... + 1103.

It is an arithmetic number, because the mean of its divisors is an integer number (42900).

2²⁵¹⁴²¹ is an apocalyptic number.

It is an amenable number.

251421 is a deficient number, since it is larger than the sum of its proper divisors (91779).

251421 is a wasteful number, since it uses less digits than its factorization.

251421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1995.

The product of its digits is 80, while the sum is 15.

The square root of 251421 is about 501.4189864774. The cubic root of 251421 is about 63.1151835861.

Adding to 251421 its reverse (124152), we get a palindrome (375573).

The spelling of 251421 in words is "two hundred fifty-one thousand, four hundred twenty-one".