991161600 has 648 divisors, whose sum is σ = 4055802912. Its totient is φ = 210124800.

The previous prime is 991161553. The next prime is 991161631. The reversal of 991161600 is 6161199.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 52166391 + ... + 52166409.

Almost surely, 2^991161600 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 991161600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2027901456).

991161600 is an abundant number, since it is smaller than the sum of its proper divisors (3064641312).

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

991161600 is a wasteful number, since it uses less digits than its factorization.

991161600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 33.

The square root of 991161600 is about 31482.7190693561. The cubic root of 991161600 is about 997.0451440930.

The spelling of 991161600 in words is "nine hundred ninety-one million, one hundred sixty-one thousand, six hundred".