988991 has 4 divisors (see below), whose sum is σ = 990984. Its totient is φ = 987000.

The previous prime is 988979. The next prime is 989011. The reversal of 988991 is 199889.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-988991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (988901) 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, 416 + ... + 1466.

It is an arithmetic number, because the mean of its divisors is an integer number (247746).

2⁹⁸⁸⁹⁹¹ is an apocalyptic number.

988991 is a deficient number, since it is larger than the sum of its proper divisors (1993).

988991 is a wasteful number, since it uses less digits than its factorization.

988991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1992.

The product of its digits is 46656, while the sum is 44.

The square root of 988991 is about 994.4802662698. The cubic root of 988991 is about 99.6316783908.

The spelling of 988991 in words is "nine hundred eighty-eight thousand, nine hundred ninety-one".