20913569906 has 4 divisors (see below), whose sum is σ = 31370354862. Its totient is φ = 10456784952.

The previous prime is 20913569899. The next prime is 20913569909. The reversal of 20913569906 is 60996531902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 60996531902 = 2 ⋅30498265951.

It can be written as a sum of positive squares in only one way, i.e., 11511358681 + 9402211225 = 107291^2 + 96965^2 .

It is not an unprimeable number, because it can be changed into a prime (20913569909) 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 as a sum of consecutive naturals, namely, 5228392475 + ... + 5228392478.

Almost surely, 2^20913569906 is an apocalyptic number.

20913569906 is a deficient number, since it is larger than the sum of its proper divisors (10456784956).

20913569906 is a wasteful number, since it uses less digits than its factorization.

20913569906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10456784955.

The product of its (nonzero) digits is 787320, while the sum is 50.

The spelling of 20913569906 in words is "twenty billion, nine hundred thirteen million, five hundred sixty-nine thousand, nine hundred six".