20985311506 has 12 divisors (see below), whose sum is σ = 32264453466. Its totient is φ = 10236735680.

The previous prime is 20985311453. The next prime is 20985311507. The reversal of 20985311506 is 60511358902.

It can be written as a sum of positive squares in 3 ways, for example, as 6659376025 + 14325935481 = 81605^2 + 119691^2 .

It is not an unprimeable number, because it can be changed into a prime (20985311507) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3117595 + ... + 3124318.

Almost surely, 2^20985311506 is an apocalyptic number.

20985311506 is a deficient number, since it is larger than the sum of its proper divisors (11279141960).

20985311506 is an equidigital number, since it uses as much as digits as its factorization.

20985311506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6241997 (or 6241956 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 40.

The spelling of 20985311506 in words is "twenty billion, nine hundred eighty-five million, three hundred eleven thousand, five hundred six".