2019991 has 8 divisors (see below), whose sum is σ = 2208384. Its totient is φ = 1839360.

The previous prime is 2019977. The next prime is 2020001. The reversal of 2019991 is 1999102.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2019991 - 2⁵ = 2019959 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

2019991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2019911) 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 in 7 ways as a sum of consecutive naturals, for example, 1390 + ... + 2443.

It is an arithmetic number, because the mean of its divisors is an integer number (276048).

2^2019991 is an apocalyptic number.

2019991 is a deficient number, since it is larger than the sum of its proper divisors (188393).

2019991 is a wasteful number, since it uses less digits than its factorization.

2019991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3881.

The product of its (nonzero) digits is 1458, while the sum is 31.

The square root of 2019991 is about 1421.2638741627. The cubic root of 2019991 is about 126.4104987474.

The spelling of 2019991 in words is "two million, nineteen thousand, nine hundred ninety-one".