21203123106 has 64 divisors (see below), whose sum is σ = 47076503040. Its totient is φ = 6312936960.

The previous prime is 21203123099. The next prime is 21203123107. The reversal of 21203123106 is 60132130212.

It is not an unprimeable number, because it can be changed into a prime (21203123107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 877965 + ... + 901791.

It is an arithmetic number, because the mean of its divisors is an integer number (735570360).

Almost surely, 2^21203123106 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21203123106, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23538251520).

21203123106 is an abundant number, since it is smaller than the sum of its proper divisors (25873379934).

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

21203123106 is a wasteful number, since it uses less digits than its factorization.

21203123106 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24079.

The product of its (nonzero) digits is 432, while the sum is 21.

Adding to 21203123106 its reverse (60132130212), we get a palindrome (81335253318).

The spelling of 21203123106 in words is "twenty-one billion, two hundred three million, one hundred twenty-three thousand, one hundred six".