42778039921 has 4 divisors (see below), whose sum is σ = 42781072372. Its totient is φ = 42775007472.

The previous prime is 42778039873. The next prime is 42778039939. The reversal of 42778039921 is 12993087724.

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 27942799921 + 14835240000 = 167161^2 + 121800^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42778039921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42778039951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1494966 + ... + 1523311.

It is an arithmetic number, because the mean of its divisors is an integer number (10695268093).

Almost surely, 2^42778039921 is an apocalyptic number.

It is an amenable number.

42778039921 is a deficient number, since it is larger than the sum of its proper divisors (3032451).

42778039921 is a wasteful number, since it uses less digits than its factorization.

42778039921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3032450.

The product of its (nonzero) digits is 1524096, while the sum is 52.

The spelling of 42778039921 in words is "forty-two billion, seven hundred seventy-eight million, thirty-nine thousand, nine hundred twenty-one".