1995991 has 2 divisors, whose sum is σ = 1995992. Its totient is φ = 1995990.

The previous prime is 1995989. The next prime is 1996013.

1995991 is nontrivially palindromic in base 10.

It is a weak prime.

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 1995991 - 2¹ = 1995989 is a prime.

Together with 1995989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1995971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 997995 + 997996.

It is an arithmetic number, because the mean of its divisors is an integer number (997996).

2^1995991 is an apocalyptic number.

1995991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1995991 is an equidigital number, since it uses as much as digits as its factorization.

1995991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32805, while the sum is 43.

The square root of 1995991 is about 1412.7954558251. The cubic root of 1995991 is about 125.9078649532.

The spelling of 1995991 in words is "one million, nine hundred ninety-five thousand, nine hundred ninety-one".