21123101321 has 8 divisors (see below), whose sum is σ = 24144078144. Its totient is φ = 18102972240.

The previous prime is 21123101309. The next prime is 21123101333. The reversal of 21123101321 is 12310132112.

It is an interprime number because it is at equal distance from previous prime (21123101309) and next prime (21123101333).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21123101321 - 2⁶ = 21123101257 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 21123101321.

It is not an unprimeable number, because it can be changed into a prime (21123101521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 157610 + ... + 259011.

It is an arithmetic number, because the mean of its divisors is an integer number (3018009768).

Almost surely, 2^21123101321 is an apocalyptic number.

It is an amenable number.

21123101321 is a deficient number, since it is larger than the sum of its proper divisors (3020976823).

21123101321 is an equidigital number, since it uses as much as digits as its factorization.

21123101321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423871.

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

Adding to 21123101321 its reverse (12310132112), we get a palindrome (33433233433).

The spelling of 21123101321 in words is "twenty-one billion, one hundred twenty-three million, one hundred one thousand, three hundred twenty-one".