989720891 has 4 divisors (see below), whose sum is σ = 993099072. Its totient is φ = 986342712.

The previous prime is 989720873. The next prime is 989720899. The reversal of 989720891 is 198027989.

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

It is a cyclic number.

It is not a de Polignac number, because 989720891 - 2⁶ = 989720827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (989720899) 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, 1688651 + ... + 1689236.

It is an arithmetic number, because the mean of its divisors is an integer number (248274768).

Almost surely, 2^989720891 is an apocalyptic number.

989720891 is a deficient number, since it is larger than the sum of its proper divisors (3378181).

989720891 is a wasteful number, since it uses less digits than its factorization.

989720891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3378180.

The product of its (nonzero) digits is 653184, while the sum is 53.

The square root of 989720891 is about 31459.8297992853. The cubic root of 989720891 is about 996.5618228186.

The spelling of 989720891 in words is "nine hundred eighty-nine million, seven hundred twenty thousand, eight hundred ninety-one".