991134478 has 4 divisors (see below), whose sum is σ = 1486701720. Its totient is φ = 495567238.

The previous prime is 991134439. The next prime is 991134491. The reversal of 991134478 is 874431199.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 874431199 = 21397 ⋅40867.

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, 247783618 + ... + 247783621.

It is an arithmetic number, because the mean of its divisors is an integer number (371675430).

Almost surely, 2^991134478 is an apocalyptic number.

991134478 is a deficient number, since it is larger than the sum of its proper divisors (495567242).

991134478 is a wasteful number, since it uses less digits than its factorization.

991134478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495567241.

The product of its digits is 217728, while the sum is 46.

The square root of 991134478 is about 31482.2883221662. The cubic root of 991134478 is about 997.0360496779.

The spelling of 991134478 in words is "nine hundred ninety-one million, one hundred thirty-four thousand, four hundred seventy-eight".