16640993 has 4 divisors (see below), whose sum is σ = 16955028. Its totient is φ = 16326960.

The previous prime is 16640969. The next prime is 16640999. The reversal of 16640993 is 39904661.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8392609 + 8248384 = 2897^2 + 2872^2 .

It is a cyclic number.

It is not a de Polignac number, because 16640993 - 2¹⁰ = 16639969 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16640999) 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, 156938 + ... + 157043.

It is an arithmetic number, because the mean of its divisors is an integer number (4238757).

Almost surely, 2^16640993 is an apocalyptic number.

It is an amenable number.

16640993 is a deficient number, since it is larger than the sum of its proper divisors (314035).

16640993 is an equidigital number, since it uses as much as digits as its factorization.

16640993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 314034.

The product of its (nonzero) digits is 34992, while the sum is 38.

The square root of 16640993 is about 4079.3373236348. The cubic root of 16640993 is about 255.3052502402.

The spelling of 16640993 in words is "sixteen million, six hundred forty thousand, nine hundred ninety-three".