42778821 has 8 divisors (see below), whose sum is σ = 57068704. Its totient is φ = 28504080.

The previous prime is 42778819. The next prime is 42778847. The reversal of 42778821 is 12887724.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 42778821 - 2¹ = 42778819 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 42778821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42778811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8610 + ... + 12636.

It is an arithmetic number, because the mean of its divisors is an integer number (7133588).

Almost surely, 2^42778821 is an apocalyptic number.

It is an amenable number.

42778821 is a deficient number, since it is larger than the sum of its proper divisors (14289883).

42778821 is a wasteful number, since it uses less digits than its factorization.

42778821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7571.

The product of its digits is 50176, while the sum is 39.

The square root of 42778821 is about 6540.5520409213. The cubic root of 42778821 is about 349.7380924970.

The spelling of 42778821 in words is "forty-two million, seven hundred seventy-eight thousand, eight hundred twenty-one".