1965991 has 4 divisors (see below), whose sum is σ = 2013984. Its totient is φ = 1918000.

The previous prime is 1965983. The next prime is 1966007. The reversal of 1965991 is 1995691.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1965991 - 2³ = 1965983 is a prime.

It is a super-2 number, since 2×1965991² = 7730241224162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1965941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23935 + ... + 24016.

It is an arithmetic number, because the mean of its divisors is an integer number (503496).

2^1965991 is an apocalyptic number.

1965991 is a deficient number, since it is larger than the sum of its proper divisors (47993).

1965991 is an equidigital number, since it uses as much as digits as its factorization.

1965991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47992.

The product of its digits is 21870, while the sum is 40.

The square root of 1965991 is about 1402.1380103257. The cubic root of 1965991 is about 125.2738741719.

The spelling of 1965991 in words is "one million, nine hundred sixty-five thousand, nine hundred ninety-one".