21033312321 has 32 divisors (see below), whose sum is σ = 32655283200. Its totient is φ = 11793107520.

The previous prime is 21033312281. The next prime is 21033312329. The reversal of 21033312321 is 12321333012.

It is not a de Polignac number, because 21033312321 - 2⁶ = 21033312257 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21033312329) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 654610 + ... + 685988.

It is an arithmetic number, because the mean of its divisors is an integer number (1020477600).

Almost surely, 2^21033312321 is an apocalyptic number.

21033312321 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21033312321 is a deficient number, since it is larger than the sum of its proper divisors (11621970879).

21033312321 is a wasteful number, since it uses less digits than its factorization.

21033312321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31989.

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

Adding to 21033312321 its reverse (12321333012), we get a palindrome (33354645333).

The spelling of 21033312321 in words is "twenty-one billion, thirty-three million, three hundred twelve thousand, three hundred twenty-one".