42009531 has 4 divisors (see below), whose sum is σ = 56012712. Its totient is φ = 28006352.

The previous prime is 42009509. The next prime is 42009571. The reversal of 42009531 is 13590024.

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

It is a cyclic number.

It is not a de Polignac number, because 42009531 - 2⁷ = 42009403 is a prime.

It is a super-2 number, since 2×42009531² = 3529601389679922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (42009571) 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, 7001586 + ... + 7001591.

It is an arithmetic number, because the mean of its divisors is an integer number (14003178).

Almost surely, 2^42009531 is an apocalyptic number.

42009531 is a deficient number, since it is larger than the sum of its proper divisors (14003181).

42009531 is a wasteful number, since it uses less digits than its factorization.

42009531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14003180.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 42009531 is about 6481.4759893098. The cubic root of 42009531 is about 347.6289561587.

Adding to 42009531 its reverse (13590024), we get a palindrome (55599555).

It can be divided in two parts, 4200 and 9531, that added together give a palindrome (13731).

The spelling of 42009531 in words is "forty-two million, nine thousand, five hundred thirty-one".