991618 has 8 divisors (see below), whose sum is σ = 1502460. Its totient is φ = 490800.

The previous prime is 991607. The next prime is 991619. The reversal of 991618 is 816199.

It can be written as a sum of positive squares in 2 ways, for example, as 635209 + 356409 = 797^2 + 597^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (991619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2253 + ... + 2656.

2⁹⁹¹⁶¹⁸ is an apocalyptic number.

991618 is a deficient number, since it is larger than the sum of its proper divisors (510842).

991618 is a wasteful number, since it uses less digits than its factorization.

991618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5012.

The product of its digits is 3888, while the sum is 34.

The square root of 991618 is about 995.8001807592. The cubic root of 991618 is about 99.7198157008.

The spelling of 991618 in words is "nine hundred ninety-one thousand, six hundred eighteen".