991797 has 8 divisors (see below), whose sum is σ = 1400256. Its totient is φ = 622272.

The previous prime is 991777. The next prime is 991811. The reversal of 991797 is 797199.

991797 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 not a de Polignac number, because 991797 - 2⁶ = 991733 is a prime.

It is a super-2 number, since 2×991797² = 1967322578418, which contains 22 as substring.

It is an Ulam number.

991797 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991717) 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, 9673 + ... + 9774.

It is an arithmetic number, because the mean of its divisors is an integer number (175032).

2⁹⁹¹⁷⁹⁷ is an apocalyptic number.

It is an amenable number.

991797 is a deficient number, since it is larger than the sum of its proper divisors (408459).

991797 is a wasteful number, since it uses less digits than its factorization.

991797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19467.

The product of its digits is 35721, while the sum is 42.

The square root of 991797 is about 995.8900541726. The cubic root of 991797 is about 99.7258155828.

It can be divided in two parts, 9 and 91797, that added together give a triangular number (91806 = T₄₂₈).

The spelling of 991797 in words is "nine hundred ninety-one thousand, seven hundred ninety-seven".