42049781 has 4 divisors (see below), whose sum is σ = 42317772. Its totient is φ = 41781792.

The previous prime is 42049769. The next prime is 42049783. The reversal of 42049781 is 18794024.

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 5640625 + 36409156 = 2375^2 + 6034^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42049781 is a prime.

It is a super-2 number, since 2×42049781² = 3536368164295922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42049783) 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, 133760 + ... + 134073.

It is an arithmetic number, because the mean of its divisors is an integer number (10579443).

Almost surely, 2^42049781 is an apocalyptic number.

It is an amenable number.

42049781 is a deficient number, since it is larger than the sum of its proper divisors (267991).

42049781 is a wasteful number, since it uses less digits than its factorization.

42049781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267990.

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 42049781 is about 6484.5802485589. The cubic root of 42049781 is about 347.7399436644.

The spelling of 42049781 in words is "forty-two million, forty-nine thousand, seven hundred eighty-one".