20401 has 4 divisors (see below), whose sum is σ = 21312. Its totient is φ = 19492.
The previous prime is 20399. The next prime is 20407. The reversal of 20401 is 10402.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.
It is a cyclic number.
It is not a de Polignac number, because 20401 - 21 = 20399 is a prime.
It is a Duffinian number.
It is a nialpdrome in base 12.
It is not an unprimeable number, because it can be changed into a prime (20407) 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, 421 + ... + 466.
It is an arithmetic number, because the mean of its divisors is an integer number (5328).
220401 is an apocalyptic number.
It is an amenable number.
20401 is a deficient number, since it is larger than the sum of its proper divisors (911).
20401 is an equidigital number, since it uses as much as digits as its factorization.
20401 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 910.
The product of its (nonzero) digits is 8, while the sum is 7.
The square root of 20401 is about 142.8320692282. The cubic root of 20401 is about 27.3243906233.
Adding to 20401 its reverse (10402), we get a palindrome (30803).
Subtracting from 20401 its reverse (10402), we obtain a palindrome (9999).
The spelling of 20401 in words is "twenty thousand, four hundred one", and thus it is an iban number.
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