664415678 has 4 divisors (see below), whose sum is σ = 996623520. Its totient is φ = 332207838.

The previous prime is 664415621. The next prime is 664415681. The reversal of 664415678 is 876514466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 876514466 = 2 ⋅438257233.

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, 166103918 + ... + 166103921.

It is an arithmetic number, because the mean of its divisors is an integer number (249155880).

Almost surely, 2^664415678 is an apocalyptic number.

664415678 is a deficient number, since it is larger than the sum of its proper divisors (332207842).

664415678 is a wasteful number, since it uses less digits than its factorization.

664415678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332207841.

The product of its digits is 967680, while the sum is 47.

The square root of 664415678 is about 25776.2619089735. The cubic root of 664415678 is about 872.5961461959.

It can be divided in two parts, 6644 and 15678, that added together give a palindrome (22322).

The spelling of 664415678 in words is "six hundred sixty-four million, four hundred fifteen thousand, six hundred seventy-eight".