1991519 has 2 divisors, whose sum is σ = 1991520. Its totient is φ = 1991518.

The previous prime is 1991503. The next prime is 1991527. The reversal of 1991519 is 9151991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1991519 - 2⁴ = 1991503 is a prime.

It is a super-2 number, since 2×1991519² = 7932295854722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1991819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995759 + 995760.

It is an arithmetic number, because the mean of its divisors is an integer number (995760).

2^1991519 is an apocalyptic number.

1991519 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991519 is an equidigital number, since it uses as much as digits as its factorization.

1991519 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3645, while the sum is 35.

The square root of 1991519 is about 1411.2118905395. The cubic root of 1991519 is about 125.8137628244.

The spelling of 1991519 in words is "one million, nine hundred ninety-one thousand, five hundred nineteen".