21352438818 has 24 divisors (see below), whose sum is σ = 46283847948. Its totient is φ = 7114367232.

The previous prime is 21352438741. The next prime is 21352438853. The reversal of 21352438818 is 81883425312.

21352438818 is a `hidden beast` number, since 2 + 13 + 524 + 38 + 81 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 21344333409 + 8105409 = 146097^2 + 2847^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 216871 + ... + 299562.

Almost surely, 2^21352438818 is an apocalyptic number.

21352438818 is an abundant number, since it is smaller than the sum of its proper divisors (24931409130).

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

21352438818 is a wasteful number, since it uses less digits than its factorization.

21352438818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 518738 (or 518735 counting only the distinct ones).

The product of its digits is 368640, while the sum is 45.

The spelling of 21352438818 in words is "twenty-one billion, three hundred fifty-two million, four hundred thirty-eight thousand, eight hundred eighteen".