991028016 has 120 divisors (see below), whose sum is σ = 3033448704. Its totient is φ = 299537280.

The previous prime is 991027981. The next prime is 991028023. The reversal of 991028016 is 610820199.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 1024365 + ... + 1025331.

Almost surely, 2^991028016 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991028016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1516724352).

991028016 is an abundant number, since it is smaller than the sum of its proper divisors (2042420688).

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

991028016 is a wasteful number, since it uses less digits than its factorization.

991028016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1639 (or 1630 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 991028016 is about 31480.5974530345. The cubic root of 991028016 is about 997.0003497620. Note that the first 3 decimals are identical.

The spelling of 991028016 in words is "nine hundred ninety-one million, twenty-eight thousand, sixteen".