42215021 has 4 divisors (see below), whose sum is σ = 42328572. Its totient is φ = 42101472.

The previous prime is 42215003. The next prime is 42215023. The reversal of 42215021 is 12051224.

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 8702500 + 33512521 = 2950^2 + 5789^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42215021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42215023) 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, 56216 + ... + 56961.

It is an arithmetic number, because the mean of its divisors is an integer number (10582143).

Almost surely, 2^42215021 is an apocalyptic number.

It is an amenable number.

42215021 is a deficient number, since it is larger than the sum of its proper divisors (113551).

42215021 is a wasteful number, since it uses less digits than its factorization.

42215021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113550.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 42215021 is about 6497.3087505520. The cubic root of 42215021 is about 348.1948445352.

Adding to 42215021 its reverse (12051224), we get a palindrome (54266245).

The spelling of 42215021 in words is "forty-two million, two hundred fifteen thousand, twenty-one".