991331723 has 4 divisors (see below), whose sum is σ = 992836680. Its totient is φ = 989826768.

The previous prime is 991331699. The next prime is 991331741. The reversal of 991331723 is 327133199.

991331723 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 327133199 = 967 ⋅338297.

It is a cyclic number.

It is not a de Polignac number, because 991331723 - 2¹⁰ = 991330699 is a prime.

It is a super-2 number, since 2×991331723² = 1965477170052297458, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991331753) 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, 751490 + ... + 752807.

It is an arithmetic number, because the mean of its divisors is an integer number (248209170).

Almost surely, 2^991331723 is an apocalyptic number.

991331723 is a deficient number, since it is larger than the sum of its proper divisors (1504957).

991331723 is a wasteful number, since it uses less digits than its factorization.

991331723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1504956.

The product of its digits is 30618, while the sum is 38.

The square root of 991331723 is about 31485.4208007452. The cubic root of 991331723 is about 997.1021851135.

The spelling of 991331723 in words is "nine hundred ninety-one million, three hundred thirty-one thousand, seven hundred twenty-three".