21013145105 has 4 divisors (see below), whose sum is σ = 25215774132. Its totient is φ = 16810516080.

The previous prime is 21013145081. The next prime is 21013145149. The reversal of 21013145105 is 50154131012.

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 3927779584 + 17085365521 = 62672^2 + 130711^2 .

It is not a de Polignac number, because 21013145105 - 2³² = 16718177809 is a prime.

It is a super-2 number, since 2×21013145105² (a number of 21 digits) contains 22 as substring.

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, 2101314506 + ... + 2101314515.

It is an arithmetic number, because the mean of its divisors is an integer number (6303943533).

Almost surely, 2^21013145105 is an apocalyptic number.

It is an amenable number.

21013145105 is a deficient number, since it is larger than the sum of its proper divisors (4202629027).

21013145105 is an equidigital number, since it uses as much as digits as its factorization.

21013145105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4202629026.

The product of its (nonzero) digits is 600, while the sum is 23.

Adding to 21013145105 its reverse (50154131012), we get a palindrome (71167276117).

The spelling of 21013145105 in words is "twenty-one billion, thirteen million, one hundred forty-five thousand, one hundred five".