21041555305 has 4 divisors (see below), whose sum is σ = 25249866372. Its totient is φ = 16833244240.

The previous prime is 21041555239. The next prime is 21041555323. The reversal of 21041555305 is 50355514012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10062497344 + 10979057961 = 100312^2 + 104781^2 .

It is not a de Polignac number, because 21041555305 - 2²⁵ = 21008000873 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2104155526 + ... + 2104155535.

It is an arithmetic number, because the mean of its divisors is an integer number (6312466593).

Almost surely, 2^21041555305 is an apocalyptic number.

It is an amenable number.

21041555305 is a deficient number, since it is larger than the sum of its proper divisors (4208311067).

21041555305 is an equidigital number, since it uses as much as digits as its factorization.

21041555305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4208311066.

The product of its (nonzero) digits is 15000, while the sum is 31.

The spelling of 21041555305 in words is "twenty-one billion, forty-one million, five hundred fifty-five thousand, three hundred five".