21006440938 has 16 divisors (see below), whose sum is σ = 36889360704. Its totient is φ = 8783180640.

The previous prime is 21006440927. The next prime is 21006440947. The reversal of 21006440938 is 83904460012.

It is a junction number, because it is equal to n+sod(n) for n = 21006440897 and 21006440906.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 18297720 + ... + 18298867.

It is an arithmetic number, because the mean of its divisors is an integer number (2305585044).

Almost surely, 2^21006440938 is an apocalyptic number.

21006440938 is a deficient number, since it is larger than the sum of its proper divisors (15882919766).

21006440938 is a wasteful number, since it uses less digits than its factorization.

21006440938 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36596637.

The product of its (nonzero) digits is 41472, while the sum is 37.

The spelling of 21006440938 in words is "twenty-one billion, six million, four hundred forty thousand, nine hundred thirty-eight".