21550012105 has 4 divisors (see below), whose sum is σ = 25860014532. Its totient is φ = 17240009680.

The previous prime is 21550012031. The next prime is 21550012117. The reversal of 21550012105 is 50121005512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9810506304 + 11739505801 = 99048^2 + 108349^2 .

It is not a de Polignac number, because 21550012105 - 2¹⁷ = 21549881033 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2155001206 + ... + 2155001215.

It is an arithmetic number, because the mean of its divisors is an integer number (6465003633).

Almost surely, 2^21550012105 is an apocalyptic number.

It is an amenable number.

21550012105 is a deficient number, since it is larger than the sum of its proper divisors (4310002427).

21550012105 is an equidigital number, since it uses as much as digits as its factorization.

21550012105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4310002426.

The product of its (nonzero) digits is 500, while the sum is 22.

Adding to 21550012105 its reverse (50121005512), we get a palindrome (71671017617).

The spelling of 21550012105 in words is "twenty-one billion, five hundred fifty million, twelve thousand, one hundred five".