42040021 has 8 divisors (see below), whose sum is σ = 44524224. Its totient is φ = 39610560.

The previous prime is 42040007. The next prime is 42040051. The reversal of 42040021 is 12004024.

42040021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42040021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 42039983 and 42040010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42040051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12100 + ... + 15181.

It is an arithmetic number, because the mean of its divisors is an integer number (5565528).

Almost surely, 2^42040021 is an apocalyptic number.

It is an amenable number.

42040021 is a deficient number, since it is larger than the sum of its proper divisors (2484203).

42040021 is a wasteful number, since it uses less digits than its factorization.

42040021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27371.

The product of its (nonzero) digits is 64, while the sum is 13.

The square root of 42040021 is about 6483.8276503929. The cubic root of 42040021 is about 347.7130374246.

Adding to 42040021 its reverse (12004024), we get a palindrome (54044045).

The spelling of 42040021 in words is "forty-two million, forty thousand, twenty-one".