21134105621 has 4 divisors (see below), whose sum is σ = 21140345100. Its totient is φ = 21127866144.

The previous prime is 21134105609. The next prime is 21134105639. The reversal of 21134105621 is 12650143112.

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 19396132900 + 1737972721 = 139270^2 + 41689^2 .

It is a cyclic number.

It is not a de Polignac number, because 21134105621 - 2⁶ = 21134105557 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 (21134105521) 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, 3114656 + ... + 3121433.

It is an arithmetic number, because the mean of its divisors is an integer number (5285086275).

Almost surely, 2^21134105621 is an apocalyptic number.

It is an amenable number.

21134105621 is a deficient number, since it is larger than the sum of its proper divisors (6239479).

21134105621 is an equidigital number, since it uses as much as digits as its factorization.

21134105621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6239478.

The product of its (nonzero) digits is 1440, while the sum is 26.

Adding to 21134105621 its reverse (12650143112), we get a palindrome (33784248733).

The spelling of 21134105621 in words is "twenty-one billion, one hundred thirty-four million, one hundred five thousand, six hundred twenty-one".