42187221 has 18 divisors (see below), whose sum is σ = 63708918. Its totient is φ = 26898960.

The previous prime is 42187207. The next prime is 42187253. The reversal of 42187221 is 12278124.

It can be written as a sum of positive squares in only one way, i.e., 42068196 + 119025 = 6486^2 + 345^2 .

It is not a de Polignac number, because 42187221 - 2¹³ = 42179029 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42187021) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 331 + ... + 9191.

Almost surely, 2^42187221 is an apocalyptic number.

It is an amenable number.

42187221 is a deficient number, since it is larger than the sum of its proper divisors (21521697).

42187221 is a wasteful number, since it uses less digits than its factorization.

42187221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8913 (or 8887 counting only the distinct ones).

The product of its digits is 1792, while the sum is 27.

The square root of 42187221 is about 6495.1690509178. The cubic root of 42187221 is about 348.1183951099.

The spelling of 42187221 in words is "forty-two million, one hundred eighty-seven thousand, two hundred twenty-one".