991945 has 8 divisors (see below), whose sum is σ = 1231560. Its totient is φ = 766080.

The previous prime is 991943. The next prime is 991951. The reversal of 991945 is 549199.

991945 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 203401 + 788544 = 451^2 + 888^2 .

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

It is not a de Polignac number, because 991945 - 2¹ = 991943 is a prime.

It is not an unprimeable number, because it can be changed into a prime (991943) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3276 + ... + 3565.

It is an arithmetic number, because the mean of its divisors is an integer number (153945).

2⁹⁹¹⁹⁴⁵ is an apocalyptic number.

It is an amenable number.

991945 is a deficient number, since it is larger than the sum of its proper divisors (239615).

991945 is a wasteful number, since it uses less digits than its factorization.

991945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6875.

The product of its digits is 14580, while the sum is 37.

The square root of 991945 is about 995.9643567919. The cubic root of 991945 is about 99.7307758339.

It can be divided in two parts, 99194 and 5, that added together give a palindrome (99199).

The spelling of 991945 in words is "nine hundred ninety-one thousand, nine hundred forty-five".