21511110505 has 8 divisors (see below), whose sum is σ = 26510990472. Its totient is φ = 16743783168.

The previous prime is 21511110493. The next prime is 21511110539. The reversal of 21511110505 is 50501111512.

It can be written as a sum of positive squares in 4 ways, for example, as 8830548841 + 12680561664 = 93971^2 + 112608^2 .

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 21511110505 - 2⁷ = 21511110377 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 58137952 + ... + 58138321.

It is an arithmetic number, because the mean of its divisors is an integer number (3313873809).

Almost surely, 2^21511110505 is an apocalyptic number.

It is an amenable number.

21511110505 is a deficient number, since it is larger than the sum of its proper divisors (4999879967).

21511110505 is a wasteful number, since it uses less digits than its factorization.

21511110505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116276315.

The product of its (nonzero) digits is 250, while the sum is 22.

The spelling of 21511110505 in words is "twenty-one billion, five hundred eleven million, one hundred ten thousand, five hundred five".