21943816506 has 24 divisors (see below), whose sum is σ = 47552123424. Its totient is φ = 7313499720.

The previous prime is 21943816441. The next prime is 21943816507. The reversal of 21943816506 is 60561834912.

21943816506 is a `hidden beast` number, since 21 + 9 + 43 + 81 + 6 + 506 = 666.

It is not an unprimeable number, because it can be changed into a prime (21943816507) 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, 34965 + ... + 212391.

It is an arithmetic number, because the mean of its divisors is an integer number (1981338476).

Almost surely, 2^21943816506 is an apocalyptic number.

21943816506 is an abundant number, since it is smaller than the sum of its proper divisors (25608306918).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21943816506 is a wasteful number, since it uses less digits than its factorization.

21943816506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184306 (or 184303 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 45.

The spelling of 21943816506 in words is "twenty-one billion, nine hundred forty-three million, eight hundred sixteen thousand, five hundred six".