42126781 has 4 divisors (see below), whose sum is σ = 44344000. Its totient is φ = 39909564.

The previous prime is 42126779. The next prime is 42126787. The reversal of 42126781 is 18762124.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 42126781 - 2¹ = 42126779 is a prime.

It is a super-2 number, since 2×42126781² = 3549331354843922, 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 (42126787) 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, 1108581 + ... + 1108618.

It is an arithmetic number, because the mean of its divisors is an integer number (11086000).

Almost surely, 2^42126781 is an apocalyptic number.

It is an amenable number.

42126781 is a deficient number, since it is larger than the sum of its proper divisors (2217219).

42126781 is a wasteful number, since it uses less digits than its factorization.

42126781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2217218.

The product of its digits is 5376, while the sum is 31.

The square root of 42126781 is about 6490.5146945369. The cubic root of 42126781 is about 347.9520704017.

The spelling of 42126781 in words is "forty-two million, one hundred twenty-six thousand, seven hundred eighty-one".