100421 has 4 divisors (see below), whose sum is σ = 101292. Its totient is φ = 99552.

The previous prime is 100417. The next prime is 100447. The reversal of 100421 is 124001.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 83521 + 16900 = 289^2 + 130^2 .

It is a cyclic number.

It is not a de Polignac number, because 100421 - 2² = 100417 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 100399 and 100408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100411) 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, 230 + ... + 503.

It is an arithmetic number, because the mean of its divisors is an integer number (25323).

2¹⁰⁰⁴²¹ is an apocalyptic number.

It is an amenable number.

100421 is a deficient number, since it is larger than the sum of its proper divisors (871).

100421 is an equidigital number, since it uses as much as digits as its factorization.

100421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 870.

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 100421 is about 316.8927263286. The cubic root of 100421 is about 46.4809341038.

Adding to 100421 its reverse (124001), we get a palindrome (224422).

The spelling of 100421 in words is "one hundred thousand, four hundred twenty-one", and thus it is an iban number.