21243937018 has 16 divisors (see below), whose sum is σ = 33820536744. Its totient is φ = 9973393920.

The previous prime is 21243937003. The next prime is 21243937019. The reversal of 21243937018 is 81073934212.

21243937018 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 16539760449 + 4704176569 = 128607^2 + 68587^2 .

It is not an unprimeable number, because it can be changed into a prime (21243937019) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 727755 + ... + 756382.

Almost surely, 2^21243937018 is an apocalyptic number.

21243937018 is a deficient number, since it is larger than the sum of its proper divisors (12576599726).

21243937018 is a wasteful number, since it uses less digits than its factorization.

21243937018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1484577.

The product of its (nonzero) digits is 72576, while the sum is 40.

The spelling of 21243937018 in words is "twenty-one billion, two hundred forty-three million, nine hundred thirty-seven thousand, eighteen".