991709598 has 96 divisors (see below), whose sum is σ = 2310871680. Its totient is φ = 281315520.

The previous prime is 991709597. The next prime is 991709639. The reversal of 991709598 is 895907199.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991709597) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2549188 + ... + 2549576.

It is an arithmetic number, because the mean of its divisors is an integer number (24071580).

Almost surely, 2^991709598 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991709598, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1155435840).

991709598 is an abundant number, since it is smaller than the sum of its proper divisors (1319162082).

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

991709598 is a wasteful number, since it uses less digits than its factorization.

991709598 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 550 (or 531 counting only the distinct ones).

The product of its (nonzero) digits is 1837080, while the sum is 57.

The square root of 991709598 is about 31491.4210222403. The cubic root of 991709598 is about 997.2288605462.

The spelling of 991709598 in words is "nine hundred ninety-one million, seven hundred nine thousand, five hundred ninety-eight".