42186781 has 16 divisors (see below), whose sum is σ = 52907904. Its totient is φ = 32745024.

The previous prime is 42186763. The next prime is 42186787. The reversal of 42186781 is 18768124.

It is not a de Polignac number, because 42186781 - 2⁷ = 42186653 is a prime.

It is a super-2 number, since 2×42186781² = 3559448982283922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 42186781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42186787) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 450 + ... + 9196.

It is an arithmetic number, because the mean of its divisors is an integer number (3306744).

Almost surely, 2^42186781 is an apocalyptic number.

It is an amenable number.

42186781 is a deficient number, since it is larger than the sum of its proper divisors (10721123).

42186781 is a wasteful number, since it uses less digits than its factorization.

42186781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8820.

The product of its digits is 21504, while the sum is 37.

The square root of 42186781 is about 6495.1351795017. The cubic root of 42186781 is about 348.1171848491.

The spelling of 42186781 in words is "forty-two million, one hundred eighty-six thousand, seven hundred eighty-one".