1991633 has 8 divisors (see below), whose sum is σ = 2354880. Its totient is φ = 1648080.

The previous prime is 1991623. The next prime is 1991641. The reversal of 1991633 is 3361991.

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

It is not a de Polignac number, because 1991633 - 2⁴ = 1991617 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1991633.

It is not an unprimeable number, because it can be changed into a prime (1991603) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4703 + ... + 5108.

It is an arithmetic number, because the mean of its divisors is an integer number (294360).

2^1991633 is an apocalyptic number.

It is an amenable number.

1991633 is a deficient number, since it is larger than the sum of its proper divisors (363247).

1991633 is an equidigital number, since it uses as much as digits as its factorization.

1991633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9847.

The product of its digits is 4374, while the sum is 32.

The square root of 1991633 is about 1411.2522807776. The cubic root of 1991633 is about 125.8161634200.

The spelling of 1991633 in words is "one million, nine hundred ninety-one thousand, six hundred thirty-three".