21121012105 has 8 divisors (see below), whose sum is σ = 26030220552. Its totient is φ = 16440139008.

The previous prime is 21121012103. The next prime is 21121012189. The reversal of 21121012105 is 50121012112.

It can be written as a sum of positive squares in 4 ways, for example, as 12332324601 + 8788687504 = 111051^2 + 93748^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21121012105 - 2¹ = 21121012103 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121012103) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57083632 + ... + 57084001.

It is an arithmetic number, because the mean of its divisors is an integer number (3253777569).

Almost surely, 2^21121012105 is an apocalyptic number.

It is an amenable number.

21121012105 is a deficient number, since it is larger than the sum of its proper divisors (4909208447).

21121012105 is a wasteful number, since it uses less digits than its factorization.

21121012105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114167675.

The product of its (nonzero) digits is 40, while the sum is 16.

Adding to 21121012105 its reverse (50121012112), we get a palindrome (71242024217).

The spelling of 21121012105 in words is "twenty-one billion, one hundred twenty-one million, twelve thousand, one hundred five".