20821230909 has 12 divisors (see below), whose sum is σ = 30199907452. Its totient is φ = 13823222400.

The previous prime is 20821230887. The next prime is 20821230971. The reversal of 20821230909 is 90903212802.

It can be written as a sum of positive squares in 2 ways, for example, as 11647805625 + 9173425284 = 107925^2 + 95778^2 .

It is not a de Polignac number, because 20821230909 - 2⁸ = 20821230653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20821210909) 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 11 ways as a sum of consecutive naturals, for example, 4797562 + ... + 4801899.

Almost surely, 2^20821230909 is an apocalyptic number.

It is an amenable number.

20821230909 is a deficient number, since it is larger than the sum of its proper divisors (9378676543).

20821230909 is a wasteful number, since it uses less digits than its factorization.

20821230909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9599708 (or 9599705 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

It can be divided in two parts, 208212 and 30909, that added together give a square (239121 = 489²).

The spelling of 20821230909 in words is "twenty billion, eight hundred twenty-one million, two hundred thirty thousand, nine hundred nine".