21006326663 has 16 divisors (see below), whose sum is σ = 24192853824. Its totient is φ = 17866517760.

The previous prime is 21006326633. The next prime is 21006326681. The reversal of 21006326663 is 36662360012.

It is not a de Polignac number, because 21006326663 - 2⁶ = 21006326599 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21006326633) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 823781 + ... + 848897.

It is an arithmetic number, because the mean of its divisors is an integer number (1512053364).

Almost surely, 2^21006326663 is an apocalyptic number.

21006326663 is a deficient number, since it is larger than the sum of its proper divisors (3186527161).

21006326663 is a wasteful number, since it uses less digits than its factorization.

21006326663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26042.

The product of its (nonzero) digits is 46656, while the sum is 35.

Adding to 21006326663 its reverse (36662360012), we get a palindrome (57668686675).

The spelling of 21006326663 in words is "twenty-one billion, six million, three hundred twenty-six thousand, six hundred sixty-three".