42156221 has 4 divisors (see below), whose sum is σ = 42171072. Its totient is φ = 42141372.

The previous prime is 42156173. The next prime is 42156223. The reversal of 42156221 is 12265124.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 42156221 - 2⁶ = 42156157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42156223) 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, 1691 + ... + 9336.

It is an arithmetic number, because the mean of its divisors is an integer number (10542768).

Almost surely, 2^42156221 is an apocalyptic number.

It is an amenable number.

42156221 is a deficient number, since it is larger than the sum of its proper divisors (14851).

42156221 is a wasteful number, since it uses less digits than its factorization.

42156221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14850.

The product of its digits is 960, while the sum is 23.

The square root of 42156221 is about 6492.7822233616. The cubic root of 42156221 is about 348.0331061339.

The spelling of 42156221 in words is "forty-two million, one hundred fifty-six thousand, two hundred twenty-one".