20404890993 has 4 divisors (see below), whose sum is σ = 27206521328. Its totient is φ = 13603260660.

The previous prime is 20404890977. The next prime is 20404891033. The reversal of 20404890993 is 39909840402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20404890993 - 2⁴ = 20404890977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20404890953) 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, 3400815163 + ... + 3400815168.

It is an arithmetic number, because the mean of its divisors is an integer number (6801630332).

Almost surely, 2^20404890993 is an apocalyptic number.

It is an amenable number.

20404890993 is a deficient number, since it is larger than the sum of its proper divisors (6801630335).

20404890993 is an equidigital number, since it uses as much as digits as its factorization.

20404890993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6801630334.

The product of its (nonzero) digits is 559872, while the sum is 48.

The spelling of 20404890993 in words is "twenty billion, four hundred four million, eight hundred ninety thousand, nine hundred ninety-three".