21018342538 has 8 divisors (see below), whose sum is σ = 31650189732. Its totient is φ = 10468279296.

The previous prime is 21018342529. The next prime is 21018342539. The reversal of 21018342538 is 83524381012.

It can be written as a sum of positive squares in 2 ways, for example, as 14198390649 + 6819951889 = 119157^2 + 82583^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21018342497 and 21018342506.

It is not an unprimeable number, because it can be changed into a prime (21018342539) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20445345 + ... + 20446372.

Almost surely, 2^21018342538 is an apocalyptic number.

21018342538 is a deficient number, since it is larger than the sum of its proper divisors (10631847194).

21018342538 is a wasteful number, since it uses less digits than its factorization.

21018342538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40891976.

The product of its (nonzero) digits is 46080, while the sum is 37.

The spelling of 21018342538 in words is "twenty-one billion, eighteen million, three hundred forty-two thousand, five hundred thirty-eight".