21321265553 has 8 divisors (see below), whose sum is σ = 24372767808. Its totient is φ = 18271165104.

The previous prime is 21321265541. The next prime is 21321265561. The reversal of 21321265553 is 35556212312.

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-21321265553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21321265453) 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, 317651 + ... + 378872.

It is an arithmetic number, because the mean of its divisors is an integer number (3046595976).

Almost surely, 2^21321265553 is an apocalyptic number.

It is an amenable number.

21321265553 is a deficient number, since it is larger than the sum of its proper divisors (3051502255).

21321265553 is an equidigital number, since it uses as much as digits as its factorization.

21321265553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 700903.

The product of its digits is 54000, while the sum is 35.

Adding to 21321265553 its reverse (35556212312), we get a palindrome (56877477865).

The spelling of 21321265553 in words is "twenty-one billion, three hundred twenty-one million, two hundred sixty-five thousand, five hundred fifty-three".