991401 has 8 divisors (see below), whose sum is σ = 1391520. Its totient is φ = 626112.

The previous prime is 991387. The next prime is 991409. The reversal of 991401 is 104199.

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

It is not a de Polignac number, because 991401 - 2⁷ = 991273 is a prime.

It is an Ulam number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (991409) 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, 8640 + ... + 8753.

It is an arithmetic number, because the mean of its divisors is an integer number (173940).

2⁹⁹¹⁴⁰¹ is an apocalyptic number.

It is an amenable number.

991401 is a deficient number, since it is larger than the sum of its proper divisors (400119).

991401 is a wasteful number, since it uses less digits than its factorization.

991401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17415.

The product of its (nonzero) digits is 324, while the sum is 24.

The square root of 991401 is about 995.6912171954. The cubic root of 991401 is about 99.7125411324.

The spelling of 991401 in words is "nine hundred ninety-one thousand, four hundred one".