21640345321 has 8 divisors (see below), whose sum is σ = 24737240000. Its totient is φ = 18544804848.

The previous prime is 21640345303. The next prime is 21640345369. The reversal of 21640345321 is 12354304612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21640345321 is a prime.

It is a super-2 number, since 2×21640345321² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21640340321) 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, 304071 + ... + 368428.

It is an arithmetic number, because the mean of its divisors is an integer number (3092155000).

Almost surely, 2^21640345321 is an apocalyptic number.

It is an amenable number.

21640345321 is a deficient number, since it is larger than the sum of its proper divisors (3096894679).

21640345321 is an equidigital number, since it uses as much as digits as its factorization.

21640345321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 677103.

The product of its (nonzero) digits is 17280, while the sum is 31.

Adding to 21640345321 its reverse (12354304612), we get a palindrome (33994649933).

The spelling of 21640345321 in words is "twenty-one billion, six hundred forty million, three hundred forty-five thousand, three hundred twenty-one".