665820553 has 4 divisors (see below), whose sum is σ = 700863760. Its totient is φ = 630777348.

The previous prime is 665820539. The next prime is 665820593. The reversal of 665820553 is 355028566.

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 not a de Polignac number, because 665820553 - 2²⁵ = 632266121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665820523) 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, 17521575 + ... + 17521612.

It is an arithmetic number, because the mean of its divisors is an integer number (175215940).

Almost surely, 2^665820553 is an apocalyptic number.

It is an amenable number.

665820553 is a deficient number, since it is larger than the sum of its proper divisors (35043207).

665820553 is a wasteful number, since it uses less digits than its factorization.

665820553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35043206.

The product of its (nonzero) digits is 216000, while the sum is 40.

The square root of 665820553 is about 25803.4988518999. The cubic root of 665820553 is about 873.2107340900.

The spelling of 665820553 in words is "six hundred sixty-five million, eight hundred twenty thousand, five hundred fifty-three".