21520430220505 has 8 divisors (see below), whose sum is σ = 25870879851912. Its totient is φ = 17185435118208.

The previous prime is 21520430220449. The next prime is 21520430220529. The reversal of 21520430220505 is 50502203402512.

It can be written as a sum of positive squares in 4 ways, for example, as 1696110313104 + 19824319907401 = 1302348^2 + 4452451^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21520430220505 - 2²³ = 21520421831897 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3863629212 + ... + 3863634781.

It is an arithmetic number, because the mean of its divisors is an integer number (3233859981489).

Almost surely, 2^{21520430220505} is an apocalyptic number.

It is an amenable number.

21520430220505 is a deficient number, since it is larger than the sum of its proper divisors (4350449631407).

21520430220505 is an equidigital number, since it uses as much as digits as its factorization.

21520430220505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7727264555.

The product of its (nonzero) digits is 24000, while the sum is 31.

The spelling of 21520430220505 in words is "twenty-one trillion, five hundred twenty billion, four hundred thirty million, two hundred twenty thousand, five hundred five".