43621 has 4 divisors (see below), whose sum is σ = 44044. Its totient is φ = 43200.

The previous prime is 43613. The next prime is 43627. The reversal of 43621 is 12634.

43621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12634 = 2 ⋅6317.

It can be written as a sum of positive squares in 2 ways, for example, as 12996 + 30625 = 114^2 + 175^2 .

It is a 3-Lehmer number, since φ(43621) divides (43621-1)³.

It is a cyclic number.

It is not a de Polignac number, because 43621 - 2³ = 43613 is a prime.

It is a Duffinian number.

43621 is a lucky number.

It is a nialpdrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 43595 and 43604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (43627) 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, 61 + ... + 301.

It is an arithmetic number, because the mean of its divisors is an integer number (11011).

2⁴³⁶²¹ is an apocalyptic number.

It is an amenable number.

43621 is a deficient number, since it is larger than the sum of its proper divisors (423).

43621 is a wasteful number, since it uses less digits than its factorization.

43621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422.

The product of its digits is 144, while the sum is 16.

The square root of 43621 is about 208.8564100046. The cubic root of 43621 is about 35.2018271262.

The spelling of 43621 in words is "forty-three thousand, six hundred twenty-one".