18720210135505 has 4 divisors (see below), whose sum is σ = 22464252162612. Its totient is φ = 14976168108400.

The previous prime is 18720210135479. The next prime is 18720210135527. The reversal of 18720210135505 is 50553101202781.

It is a happy number.

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 10266839964481 + 8453370171024 = 3204191^2 + 2907468^2 .

It is a de Polignac number, because none of the positive numbers 2^k-18720210135505 is a prime.

It is a Smith number, since the sum of its digits (40) 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, 1872021013546 + ... + 1872021013555.

It is an arithmetic number, because the mean of its divisors is an integer number (5616063040653).

Almost surely, 2^{18720210135505} is an apocalyptic number.

It is an amenable number.

18720210135505 is a deficient number, since it is larger than the sum of its proper divisors (3744042027107).

18720210135505 is an equidigital number, since it uses as much as digits as its factorization.

18720210135505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3744042027106.

The product of its (nonzero) digits is 84000, while the sum is 40.

The spelling of 18720210135505 in words is "eighteen trillion, seven hundred twenty billion, two hundred ten million, one hundred thirty-five thousand, five hundred five".