20689558849 has 4 divisors (see below), whose sum is σ = 20691109764. Its totient is φ = 20688007936.

The previous prime is 20689558847. The next prime is 20689558853. The reversal of 20689558849 is 94885598602.

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 19256557824 + 1433001025 = 138768^2 + 37855^2 .

It is a cyclic number.

It is not a de Polignac number, because 20689558849 - 2¹ = 20689558847 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20689558843) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 755272 + ... + 782185.

It is an arithmetic number, because the mean of its divisors is an integer number (5172777441).

Almost surely, 2^20689558849 is an apocalyptic number.

It is an amenable number.

20689558849 is a deficient number, since it is larger than the sum of its proper divisors (1550915).

20689558849 is a wasteful number, since it uses less digits than its factorization.

20689558849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1550914.

The product of its (nonzero) digits is 49766400, while the sum is 64.

The spelling of 20689558849 in words is "twenty billion, six hundred eighty-nine million, five hundred fifty-eight thousand, eight hundred forty-nine".