21102123013 has 4 divisors (see below), whose sum is σ = 21672450700. Its totient is φ = 20531795328.

The previous prime is 21102122983. The next prime is 21102123019. The reversal of 21102123013 is 31032120112.

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 18600322689 + 2501800324 = 136383^2 + 50018^2 .

It is a cyclic number.

It is not a de Polignac number, because 21102123013 - 2¹³ = 21102114821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102123019) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 285163788 + ... + 285163861.

It is an arithmetic number, because the mean of its divisors is an integer number (5418112675).

Almost surely, 2^21102123013 is an apocalyptic number.

It is an amenable number.

21102123013 is a deficient number, since it is larger than the sum of its proper divisors (570327687).

21102123013 is an equidigital number, since it uses as much as digits as its factorization.

21102123013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 570327686.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21102123013 its reverse (31032120112), we get a palindrome (52134243125).

The spelling of 21102123013 in words is "twenty-one billion, one hundred two million, one hundred twenty-three thousand, thirteen".