7171991 has 2 divisors, whose sum is σ = 7171992. Its totient is φ = 7171990.

The previous prime is 7171979. The next prime is 7171999. The reversal of 7171991 is 1991717.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 7171991 - 2¹⁰ = 7170967 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7171999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3585995 + 3585996.

It is an arithmetic number, because the mean of its divisors is an integer number (3585996).

Almost surely, 2^7171991 is an apocalyptic number.

7171991 is a deficient number, since it is larger than the sum of its proper divisors (1).

7171991 is an equidigital number, since it uses as much as digits as its factorization.

7171991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3969, while the sum is 35.

The square root of 7171991 is about 2678.0573182813. The cubic root of 7171991 is about 192.8471590102.

The spelling of 7171991 in words is "seven million, one hundred seventy-one thousand, nine hundred ninety-one".