1991027 has 2 divisors, whose sum is σ = 1991028. Its totient is φ = 1991026.

The previous prime is 1990987. The next prime is 1991047. The reversal of 1991027 is 7201991.

It is a strong prime.

It is an emirp because it is prime and its reverse (7201991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1991027 is a prime.

It is not a weakly prime, because it can be changed into another prime (1991047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995513 + 995514.

It is an arithmetic number, because the mean of its divisors is an integer number (995514).

2^1991027 is an apocalyptic number.

1991027 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991027 is an equidigital number, since it uses as much as digits as its factorization.

1991027 is an evil number, because the sum of its binary digits is even.

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

The square root of 1991027 is about 1411.0375615128. The cubic root of 1991027 is about 125.8034013081.

The spelling of 1991027 in words is "one million, nine hundred ninety-one thousand, twenty-seven".