21321320331 has 4 divisors (see below), whose sum is σ = 28428427112. Its totient is φ = 14214213552.

The previous prime is 21321320327. The next prime is 21321320351. The reversal of 21321320331 is 13302312312.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21321320331 - 2² = 21321320327 is a prime.

It is a super-2 number, since 2×21321320331² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21321320298 and 21321320307.

It is not an unprimeable number, because it can be changed into a prime (21321320351) 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, 3553553386 + ... + 3553553391.

It is an arithmetic number, because the mean of its divisors is an integer number (7107106778).

Almost surely, 2^21321320331 is an apocalyptic number.

21321320331 is a deficient number, since it is larger than the sum of its proper divisors (7107106781).

21321320331 is an equidigital number, since it uses as much as digits as its factorization.

21321320331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7107106780.

The product of its (nonzero) digits is 648, while the sum is 21.

Adding to 21321320331 its reverse (13302312312), we get a palindrome (34623632643).

The spelling of 21321320331 in words is "twenty-one billion, three hundred twenty-one million, three hundred twenty thousand, three hundred thirty-one".