991978146 has 48 divisors (see below), whose sum is σ = 2199794688. Its totient is φ = 322920000.

The previous prime is 991978139. The next prime is 991978171. The reversal of 991978146 is 641879199.

It is a junction number, because it is equal to n+sod(n) for n = 991978092 and 991978101.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 507471 + ... + 509421.

It is an arithmetic number, because the mean of its divisors is an integer number (45829056).

Almost surely, 2^991978146 is an apocalyptic number.

991978146 is an abundant number, since it is smaller than the sum of its proper divisors (1207816542).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991978146 is a wasteful number, since it uses less digits than its factorization.

991978146 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2607 (or 2604 counting only the distinct ones).

The product of its digits is 979776, while the sum is 54.

The square root of 991978146 is about 31495.6845615395. The cubic root of 991978146 is about 997.3188666149.

The spelling of 991978146 in words is "nine hundred ninety-one million, nine hundred seventy-eight thousand, one hundred forty-six".