18505561015 has 4 divisors (see below), whose sum is σ = 22206673224. Its totient is φ = 14804448808.

The previous prime is 18505561003. The next prime is 18505561049. The reversal of 18505561015 is 51016550581.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51016550581 = 47 ⋅1085458523.

It is a cyclic number.

It is not a de Polignac number, because 18505561015 - 2⁹ = 18505560503 is a prime.

It is a Duffinian number.

It is a congruent 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, 1850556097 + ... + 1850556106.

It is an arithmetic number, because the mean of its divisors is an integer number (5551668306).

Almost surely, 2^18505561015 is an apocalyptic number.

18505561015 is a deficient number, since it is larger than the sum of its proper divisors (3701112209).

18505561015 is an equidigital number, since it uses as much as digits as its factorization.

18505561015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3701112208.

The product of its (nonzero) digits is 30000, while the sum is 37.

The spelling of 18505561015 in words is "eighteen billion, five hundred five million, five hundred sixty-one thousand, fifteen".