991601 has 8 divisors (see below), whose sum is σ = 1081920. Its totient is φ = 903312.

The previous prime is 991579. The next prime is 991603. The reversal of 991601 is 106199.

991601 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 991601 - 2¹⁴ = 975217 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991601.

It is not an unprimeable number, because it can be changed into a prime (991603) 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, 620 + ... + 1538.

It is an arithmetic number, because the mean of its divisors is an integer number (135240).

2⁹⁹¹⁶⁰¹ is an apocalyptic number.

It is an amenable number.

991601 is a deficient number, since it is larger than the sum of its proper divisors (90319).

991601 is a wasteful number, since it uses less digits than its factorization.

991601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1015.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 991601 is about 995.7916448736. The cubic root of 991601 is about 99.7192458420.

The spelling of 991601 in words is "nine hundred ninety-one thousand, six hundred one".