20890340905 has 64 divisors (see below), whose sum is σ = 29678100480. Its totient is φ = 13822099200.

The previous prime is 20890340899. The next prime is 20890340909. The reversal of 20890340905 is 50904309802.

It is a happy number.

It is not a de Polignac number, because 20890340905 - 2¹¹ = 20890338857 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20890340909) 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 63 ways as a sum of consecutive naturals, for example, 35588022 + ... + 35588608.

It is an arithmetic number, because the mean of its divisors is an integer number (463720320).

Almost surely, 2^20890340905 is an apocalyptic number.

It is an amenable number.

20890340905 is a deficient number, since it is larger than the sum of its proper divisors (8787759575).

20890340905 is a wasteful number, since it uses less digits than its factorization.

20890340905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 950.

The product of its (nonzero) digits is 77760, while the sum is 40.

The spelling of 20890340905 in words is "twenty billion, eight hundred ninety million, three hundred forty thousand, nine hundred five".