978691918 has 4 divisors (see below), whose sum is σ = 1468037880. Its totient is φ = 489345958.

The previous prime is 978691897. The next prime is 978691993. The reversal of 978691918 is 819196879.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 819196879 = 743 ⋅1102553.

It is a Smith number, since the sum of its digits (58) 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 pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 244672978 + ... + 244672981.

It is an arithmetic number, because the mean of its divisors is an integer number (367009470).

Almost surely, 2^978691918 is an apocalyptic number.

978691918 is a deficient number, since it is larger than the sum of its proper divisors (489345962).

978691918 is a wasteful number, since it uses less digits than its factorization.

978691918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 489345961.

The product of its digits is 1959552, while the sum is 58.

The square root of 978691918 is about 31284.0521352334. The cubic root of 978691918 is about 992.8462519221.

The spelling of 978691918 in words is "nine hundred seventy-eight million, six hundred ninety-one thousand, nine hundred eighteen".