21621343234013 has 4 divisors (see below), whose sum is σ = 21621357668988. Its totient is φ = 21621328799040.

The previous prime is 21621343233979. The next prime is 21621343234019. The reversal of 21621343234013 is 31043234312612.

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 207013170169 + 21414330063844 = 454987^2 + 4627562^2 .

It is a cyclic number.

It is not a de Polignac number, because 21621343234013 - 2¹⁸ = 21621342971869 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 (21621343234019) 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, 4671308 + ... + 8066213.

It is an arithmetic number, because the mean of its divisors is an integer number (5405339417247).

Almost surely, 2^{21621343234013} is an apocalyptic number.

It is an amenable number.

21621343234013 is a deficient number, since it is larger than the sum of its proper divisors (14434975).

21621343234013 is a wasteful number, since it uses less digits than its factorization.

21621343234013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14434974.

The product of its (nonzero) digits is 62208, while the sum is 35.

Adding to 21621343234013 its reverse (31043234312612), we get a palindrome (52664577546625).

The spelling of 21621343234013 in words is "twenty-one trillion, six hundred twenty-one billion, three hundred forty-three million, two hundred thirty-four thousand, thirteen".