42521 has 4 divisors (see below), whose sum is σ = 43044. Its totient is φ = 42000.

The previous prime is 42509. The next prime is 42533. The reversal of 42521 is 12524.

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 is an interprime number because it is at equal distance from previous prime (42509) and next prime (42533).

It can be written as a sum of positive squares in 2 ways, for example, as 18496 + 24025 = 136^2 + 155^2 .

It is a cyclic number.

It is not a de Polignac number, because 42521 - 2⁶ = 42457 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 42496 and 42505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110 + ... + 311.

It is an arithmetic number, because the mean of its divisors is an integer number (10761).

2⁴²⁵²¹ is an apocalyptic number.

It is an amenable number.

42521 is a deficient number, since it is larger than the sum of its proper divisors (523).

42521 is a wasteful number, since it uses less digits than its factorization.

42521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 522.

The product of its digits is 80, while the sum is 14.

The square root of 42521 is about 206.2062074720. The cubic root of 42521 is about 34.9034071380.

The spelling of 42521 in words is "forty-two thousand, five hundred twenty-one".