42398581 has 4 divisors (see below), whose sum is σ = 42425100. Its totient is φ = 42372064.

The previous prime is 42398579. The next prime is 42398593. The reversal of 42398581 is 18589324.

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

It can be written as a sum of positive squares in 2 ways, for example, as 23126481 + 19272100 = 4809^2 + 4390^2 .

It is a cyclic number.

It is not a de Polignac number, because 42398581 - 2¹ = 42398579 is a prime.

It is a super-2 number, since 2×42398581² = 3595279341627122, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42398501) 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, 10696 + ... + 14113.

It is an arithmetic number, because the mean of its divisors is an integer number (10606275).

Almost surely, 2^42398581 is an apocalyptic number.

42398581 is the 3481-st centered heptagonal number.

It is an amenable number.

42398581 is a deficient number, since it is larger than the sum of its proper divisors (26519).

42398581 is a wasteful number, since it uses less digits than its factorization.

42398581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26518.

The product of its digits is 69120, while the sum is 40.

The square root of 42398581 is about 6511.4192769319. The cubic root of 42398581 is about 348.6987902010.

The spelling of 42398581 in words is "forty-two million, three hundred ninety-eight thousand, five hundred eighty-one".