20981321566 has 8 divisors (see below), whose sum is σ = 31503176640. Its totient is φ = 10480262688.

The previous prime is 20981321527. The next prime is 20981321567. The reversal of 20981321566 is 66512318902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20981321567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5196526 + ... + 5200561.

It is an arithmetic number, because the mean of its divisors is an integer number (3937897080).

Almost surely, 2^20981321566 is an apocalyptic number.

20981321566 is a deficient number, since it is larger than the sum of its proper divisors (10521855074).

20981321566 is a wasteful number, since it uses less digits than its factorization.

20981321566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10398098.

The product of its (nonzero) digits is 155520, while the sum is 43.

The spelling of 20981321566 in words is "twenty billion, nine hundred eighty-one million, three hundred twenty-one thousand, five hundred sixty-six".