42778665 has 16 divisors (see below), whose sum is σ = 76051200. Its totient is φ = 22815216.

The previous prime is 42778663. The next prime is 42778669. The reversal of 42778665 is 56687724.

It is not a de Polignac number, because 42778665 - 2¹ = 42778663 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 42778665.

It is not an unprimeable number, because it can be changed into a prime (42778663) 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, 158305 + ... + 158574.

It is an arithmetic number, because the mean of its divisors is an integer number (4753200).

Almost surely, 2^42778665 is an apocalyptic number.

42778665 is a gapful number since it is divisible by the number (45) formed by its first and last digit.

It is an amenable number.

42778665 is a deficient number, since it is larger than the sum of its proper divisors (33272535).

42778665 is a wasteful number, since it uses less digits than its factorization.

42778665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316893 (or 316887 counting only the distinct ones).

The product of its digits is 564480, while the sum is 45.

The square root of 42778665 is about 6540.5401153116. The cubic root of 42778665 is about 349.7376673707.

The spelling of 42778665 in words is "forty-two million, seven hundred seventy-eight thousand, six hundred sixty-five".