42121 has 4 divisors (see below), whose sum is σ = 42772. Its totient is φ = 41472.

The previous prime is 42101. The next prime is 42131. The reversal of 42121 is 12124.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 35721 + 6400 = 189^2 + 80^2 .

It is a 3-Lehmer number, since φ(42121) divides (42121-1)³.

It is a cyclic number.

It is not a de Polignac number, because 42121 - 2⁵ = 42089 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 42098 and 42107.

It is not an unprimeable number, because it can be changed into a prime (42101) 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, 216 + ... + 361.

It is an arithmetic number, because the mean of its divisors is an integer number (10693).

2⁴²¹²¹ is an apocalyptic number.

It is an amenable number.

42121 is a deficient number, since it is larger than the sum of its proper divisors (651).

42121 is an equidigital number, since it uses as much as digits as its factorization.

42121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 650.

The product of its digits is 16, while the sum is 10.

The square root of 42121 is about 205.2340127757. The cubic root of 42121 is about 34.7936153346.

Adding to 42121 its reverse (12124), we get a palindrome (54245).

The spelling of 42121 in words is "forty-two thousand, one hundred twenty-one", and thus it is an iban number.