2017991 has 2 divisors, whose sum is σ = 2017992. Its totient is φ = 2017990.

The previous prime is 2017987. The next prime is 2018021. The reversal of 2017991 is 1997102.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2017991 - 2² = 2017987 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2017901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1008995 + 1008996.

It is an arithmetic number, because the mean of its divisors is an integer number (1008996).

2^2017991 is an apocalyptic number.

2017991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2017991 is an equidigital number, since it uses as much as digits as its factorization.

2017991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1134, while the sum is 29.

The square root of 2017991 is about 1420.5601008053. The cubic root of 2017991 is about 126.3687651484.

It can be divided in two parts, 201 and 7991, that added together give a 13-th power (8192 = 2¹³).

The spelling of 2017991 in words is "two million, seventeen thousand, nine hundred ninety-one".