42138931 has 4 divisors (see below), whose sum is σ = 43035552. Its totient is φ = 41242312.

The previous prime is 42138883. The next prime is 42138947. The reversal of 42138931 is 13983124.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 42138931 - 2¹¹ = 42136883 is a prime.

It is a super-2 number, since 2×42138931² = 3551379011645522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 42138893 and 42138902.

It is not an unprimeable number, because it can be changed into a prime (42138961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 448240 + ... + 448333.

It is an arithmetic number, because the mean of its divisors is an integer number (10758888).

Almost surely, 2^42138931 is an apocalyptic number.

42138931 is a deficient number, since it is larger than the sum of its proper divisors (896621).

42138931 is an equidigital number, since it uses as much as digits as its factorization.

42138931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 896620.

The product of its digits is 5184, while the sum is 31.

The square root of 42138931 is about 6491.4506083001. The cubic root of 42138931 is about 347.9855187306.

The spelling of 42138931 in words is "forty-two million, one hundred thirty-eight thousand, nine hundred thirty-one".