42157991 has 4 divisors (see below), whose sum is σ = 42171984. Its totient is φ = 42144000.

The previous prime is 42157987. The next prime is 42157993. The reversal of 42157991 is 19975124.

42157991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 42157991 - 2² = 42157987 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 (42157993) 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 3 ways as a sum of consecutive naturals, for example, 410 + ... + 9191.

It is an arithmetic number, because the mean of its divisors is an integer number (10542996).

Almost surely, 2^42157991 is an apocalyptic number.

42157991 is a deficient number, since it is larger than the sum of its proper divisors (13993).

42157991 is an equidigital number, since it uses as much as digits as its factorization.

42157991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13992.

The product of its digits is 22680, while the sum is 38.

The square root of 42157991 is about 6492.9185271340. The cubic root of 42157991 is about 348.0379769846.

The spelling of 42157991 in words is "forty-two million, one hundred fifty-seven thousand, nine hundred ninety-one".