21012320106 has 32 divisors (see below), whose sum is σ = 47390978880. Its totient is φ = 6899566608.

The previous prime is 21012320099. The next prime is 21012320107. The reversal of 21012320106 is 60102321012.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21012320107) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 2900241 + ... + 2907476.

It is an arithmetic number, because the mean of its divisors is an integer number (1480968090).

Almost surely, 2^21012320106 is an apocalyptic number.

21012320106 is an abundant number, since it is smaller than the sum of its proper divisors (26378658774).

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

21012320106 is a wasteful number, since it uses less digits than its factorization.

21012320106 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5807795 (or 5807789 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21012320106 its reverse (60102321012), we get a palindrome (81114641118).

The spelling of 21012320106 in words is "twenty-one billion, twelve million, three hundred twenty thousand, one hundred six".