42005021 has 4 divisors (see below), whose sum is σ = 43453500. Its totient is φ = 40556544.

The previous prime is 42004979. The next prime is 42005053. The reversal of 42005021 is 12050024.

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 12996025 + 29008996 = 3605^2 + 5386^2 .

It is a cyclic number.

It is not a de Polignac number, because 42005021 - 2⁶ = 42004957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 42004987 and 42005005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42005071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 724196 + ... + 724253.

It is an arithmetic number, because the mean of its divisors is an integer number (10863375).

Almost surely, 2^42005021 is an apocalyptic number.

It is an amenable number.

42005021 is a deficient number, since it is larger than the sum of its proper divisors (1448479).

42005021 is a wasteful number, since it uses less digits than its factorization.

42005021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1448478.

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

The square root of 42005021 is about 6481.1280653911. The cubic root of 42005021 is about 347.6165156270.

Adding to 42005021 its reverse (12050024), we get a palindrome (54055045).

The spelling of 42005021 in words is "forty-two million, five thousand, twenty-one".