15421 has 4 divisors (see below), whose sum is σ = 17632.
Its totient is φ = 13212.
The previous prime is 15413. The next prime is 15427. The reversal of 15421 is 12451.
Adding to 15421 its reverse (12451), we get a palindrome (27872).
It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is not a de Polignac number, because 15421 - 23 = 15413 is a prime.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (15427) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1095 + ... + 1108.
It is an arithmetic number, because the mean of its divisors is an integer number (4408).
215421 is an apocalyptic number.
It is an amenable number.
15421 is a deficient number, since it is larger than the sum of its proper divisors (2211).
15421 is an equidigital number, since it uses as much as digits as its factorization.
15421 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 2210.
The product of its digits is 40, while the sum is 13.
The square root of 15421 is about 124.1813190460.
The cubic root of 15421 is about 24.8907230378.
The spelling of 15421 in words is "fifteen thousand, four hundred twenty-one".