1665564613555 has 8 divisors (see below), whose sum is σ = 1998722835072. Its totient is φ = 1332421491648.

The previous prime is 1665564613523. The next prime is 1665564613613. The reversal of 1665564613555 is 5553164655661.

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 1665564613555 - 2⁵ = 1665564613523 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1665564613555.

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, 3530794 + ... + 3974623.

It is an arithmetic number, because the mean of its divisors is an integer number (249840354384).

Almost surely, 2^{1665564613555} is an apocalyptic number.

1665564613555 is a deficient number, since it is larger than the sum of its proper divisors (333158221517).

1665564613555 is an equidigital number, since it uses as much as digits as its factorization.

1665564613555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7549805.

The product of its digits is 48600000, while the sum is 58.

The spelling of 1665564613555 in words is "one trillion, six hundred sixty-five billion, five hundred sixty-four million, six hundred thirteen thousand, five hundred fifty-five".