991383478 has 16 divisors (see below), whose sum is σ = 1505666880. Its totient is φ = 489520000.

The previous prime is 991383461. The next prime is 991383479. The reversal of 991383478 is 874383199.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991383479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74883 + ... + 87121.

It is an arithmetic number, because the mean of its divisors is an integer number (94104180).

Almost surely, 2^991383478 is an apocalyptic number.

991383478 is a deficient number, since it is larger than the sum of its proper divisors (514283402).

991383478 is a wasteful number, since it uses less digits than its factorization.

991383478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12743.

The product of its digits is 1306368, while the sum is 52.

The square root of 991383478 is about 31486.2426783508. The cubic root of 991383478 is about 997.1195368988.

The spelling of 991383478 in words is "nine hundred ninety-one million, three hundred eighty-three thousand, four hundred seventy-eight".