21021003805 has 8 divisors (see below), whose sum is σ = 25423828992. Its totient is φ = 16684386768.

The previous prime is 21021003797. The next prime is 21021003811. The reversal of 21021003805 is 50830012012.

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

It is a cyclic number.

It is not a de Polignac number, because 21021003805 - 2³ = 21021003797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16551337 + ... + 16552606.

It is an arithmetic number, because the mean of its divisors is an integer number (3177978624).

Almost surely, 2^21021003805 is an apocalyptic number.

It is an amenable number.

21021003805 is a deficient number, since it is larger than the sum of its proper divisors (4402825187).

21021003805 is a wasteful number, since it uses less digits than its factorization.

21021003805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33104075.

The product of its (nonzero) digits is 480, while the sum is 22.

Adding to 21021003805 its reverse (50830012012), we get a palindrome (71851015817).

The spelling of 21021003805 in words is "twenty-one billion, twenty-one million, three thousand, eight hundred five".