1665520055557 has 4 divisors (see below), whose sum is σ = 1737933971040. Its totient is φ = 1593106140076.

The previous prime is 1665520055531. The next prime is 1665520055597. The reversal of 1665520055557 is 7555500255661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1665520055557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665520055597) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36206957707 + ... + 36206957752.

It is an arithmetic number, because the mean of its divisors is an integer number (434483492760).

Almost surely, 2^{1665520055557} is an apocalyptic number.

It is an amenable number.

1665520055557 is a deficient number, since it is larger than the sum of its proper divisors (72413915483).

1665520055557 is an equidigital number, since it uses as much as digits as its factorization.

1665520055557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72413915482.

The product of its (nonzero) digits is 7875000, while the sum is 52.

The spelling of 1665520055557 in words is "one trillion, six hundred sixty-five billion, five hundred twenty million, fifty-five thousand, five hundred fifty-seven".