665550066551 has 4 divisors (see below), whose sum is σ = 665559251352. Its totient is φ = 665540881752.

The previous prime is 665550066541. The next prime is 665550066563. The reversal of 665550066551 is 155660055566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 155660055566 = 2 ⋅77830027783.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665550066551 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 665550066551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665550066541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4482836 + ... + 4628921.

It is an arithmetic number, because the mean of its divisors is an integer number (166389812838).

Almost surely, 2^665550066551 is an apocalyptic number.

665550066551 is a deficient number, since it is larger than the sum of its proper divisors (9184801).

665550066551 is an equidigital number, since it uses as much as digits as its factorization.

665550066551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9184800.

The product of its (nonzero) digits is 4050000, while the sum is 50.

The spelling of 665550066551 in words is "six hundred sixty-five billion, five hundred fifty million, sixty-six thousand, five hundred fifty-one".