21312101321 has 4 divisors (see below), whose sum is σ = 24356687232. Its totient is φ = 18267515412.

The previous prime is 21312101273. The next prime is 21312101339. The reversal of 21312101321 is 12310121312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21312101321 - 2¹⁰ = 21312100297 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21312101321.

It is not an unprimeable number, because it can be changed into a prime (21312101381) 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, 1522292945 + ... + 1522292958.

It is an arithmetic number, because the mean of its divisors is an integer number (6089171808).

Almost surely, 2^21312101321 is an apocalyptic number.

It is an amenable number.

21312101321 is a deficient number, since it is larger than the sum of its proper divisors (3044585911).

21312101321 is an equidigital number, since it uses as much as digits as its factorization.

21312101321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3044585910.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 21312101321 its reverse (12310121312), we get a palindrome (33622222633).

The spelling of 21312101321 in words is "twenty-one billion, three hundred twelve million, one hundred one thousand, three hundred twenty-one".