21398839688 has 12 divisors (see below), whose sum is σ = 40123600215. Its totient is φ = 10699212968.

The previous prime is 21398839687. The next prime is 21398839691. The reversal of 21398839688 is 88693889312.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in only one way, i.e., 10699419844 + 10699419844 = 103438^2 + 103438^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=103438.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21398839687) 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 2 ways as a sum of consecutive naturals, for example, 387893 + ... + 439611.

Almost surely, 2^21398839688 is an apocalyptic number.

It is an amenable number.

21398839688 is a deficient number, since it is larger than the sum of its proper divisors (18724760527).

21398839688 is an frugal number, since it uses more digits than its factorization.

21398839688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103444 (or 51721 counting only the distinct ones).

The product of its digits is 35831808, while the sum is 65.

The spelling of 21398839688 in words is "twenty-one billion, three hundred ninety-eight million, eight hundred thirty-nine thousand, six hundred eighty-eight".