20983927821 has 4 divisors (see below), whose sum is σ = 27978570432. Its totient is φ = 13989285212.

The previous prime is 20983927763. The next prime is 20983927829. The reversal of 20983927821 is 12872938902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20983927821 - 2¹⁷ = 20983796749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20983927829) 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 3 ways as a sum of consecutive naturals, for example, 3497321301 + ... + 3497321306.

It is an arithmetic number, because the mean of its divisors is an integer number (6994642608).

Almost surely, 2^20983927821 is an apocalyptic number.

It is an amenable number.

20983927821 is a deficient number, since it is larger than the sum of its proper divisors (6994642611).

20983927821 is an equidigital number, since it uses as much as digits as its factorization.

20983927821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6994642610.

The product of its (nonzero) digits is 870912, while the sum is 51.

The spelling of 20983927821 in words is "twenty billion, nine hundred eighty-three million, nine hundred twenty-seven thousand, eight hundred twenty-one".