21165503106 has 64 divisors (see below), whose sum is σ = 46592257536. Its totient is φ = 6356563200.

The previous prime is 21165503071. The next prime is 21165503113. The reversal of 21165503106 is 60130556112.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11299386 + ... + 11301258.

It is an arithmetic number, because the mean of its divisors is an integer number (728004024).

Almost surely, 2^21165503106 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21165503106, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23296128768).

21165503106 is an abundant number, since it is smaller than the sum of its proper divisors (25426754430).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21165503106 is a wasteful number, since it uses less digits than its factorization.

21165503106 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3327.

The product of its (nonzero) digits is 5400, while the sum is 30.

The spelling of 21165503106 in words is "twenty-one billion, one hundred sixty-five million, five hundred three thousand, one hundred six".