717991 has 16 divisors (see below), whose sum is σ = 829440. Its totient is φ = 617760.

The previous prime is 717989. The next prime is 718007. The reversal of 717991 is 199717.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 717991 - 2¹ = 717989 is a prime.

It is a super-2 number, since 2×717991² = 1031022152162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (717091) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13521 + ... + 13573.

It is an arithmetic number, because the mean of its divisors is an integer number (51840).

2⁷¹⁷⁹⁹¹ is an apocalyptic number.

717991 is a deficient number, since it is larger than the sum of its proper divisors (111449).

717991 is a wasteful number, since it uses less digits than its factorization.

717991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126.

The product of its digits is 3969, while the sum is 34.

The square root of 717991 is about 847.3434958740. The cubic root of 717991 is about 89.5446548488.

The spelling of 717991 in words is "seven hundred seventeen thousand, nine hundred ninety-one".