21210145321 has 4 divisors (see below), whose sum is σ = 21294648144. Its totient is φ = 21125642500.

The previous prime is 21210145273. The next prime is 21210145357. The reversal of 21210145321 is 12354101212.

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 a de Polignac number, because none of the positive numbers 2^k-21210145321 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210145292 and 21210145301.

It is not an unprimeable number, because it can be changed into a prime (21210149321) 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, 42251035 + ... + 42251536.

It is an arithmetic number, because the mean of its divisors is an integer number (5323662036).

Almost surely, 2^21210145321 is an apocalyptic number.

It is an amenable number.

21210145321 is a deficient number, since it is larger than the sum of its proper divisors (84502823).

21210145321 is an equidigital number, since it uses as much as digits as its factorization.

21210145321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84502822.

The product of its (nonzero) digits is 480, while the sum is 22.

Adding to 21210145321 its reverse (12354101212), we get a palindrome (33564246533).

The spelling of 21210145321 in words is "twenty-one billion, two hundred ten million, one hundred forty-five thousand, three hundred twenty-one".