20991009212 has 6 divisors (see below), whose sum is σ = 36734266128. Its totient is φ = 10495504604.

The previous prime is 20991009211. The next prime is 20991009223. The reversal of 20991009212 is 21290019902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20991009211) 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, 2623876148 + ... + 2623876155.

It is an arithmetic number, because the mean of its divisors is an integer number (6122377688).

Almost surely, 2^20991009212 is an apocalyptic number.

It is an amenable number.

20991009212 is a deficient number, since it is larger than the sum of its proper divisors (15743256916).

20991009212 is a wasteful number, since it uses less digits than its factorization.

20991009212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5247752307 (or 5247752305 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 35.

The spelling of 20991009212 in words is "twenty billion, nine hundred ninety-one million, nine thousand, two hundred twelve".