394217878 has 4 divisors (see below), whose sum is σ = 591326820. Its totient is φ = 197108938.

The previous prime is 394217867. The next prime is 394217893. The reversal of 394217878 is 878712493.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 98554468 + ... + 98554471.

It is an arithmetic number, because the mean of its divisors is an integer number (147831705).

Almost surely, 2^394217878 is an apocalyptic number.

394217878 is a deficient number, since it is larger than the sum of its proper divisors (197108942).

394217878 is a wasteful number, since it uses less digits than its factorization.

394217878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197108941.

The product of its digits is 677376, while the sum is 49.

The square root of 394217878 is about 19854.9207502825. The cubic root of 394217878 is about 733.2388010837.

The spelling of 394217878 in words is "three hundred ninety-four million, two hundred seventeen thousand, eight hundred seventy-eight".