665820555 has 16 divisors (see below), whose sum is σ = 1127978784. Its totient is φ = 334215680.

The previous prime is 665820539. The next prime is 665820593. The reversal of 665820555 is 555028566.

It is not a de Polignac number, because 665820555 - 2⁴ = 665820539 is a prime.

It is a super-2 number, since 2×665820555² = 886634022921016050, which contains 22 as substring.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 1305276 + ... + 1305785.

It is an arithmetic number, because the mean of its divisors is an integer number (70498674).

Almost surely, 2^665820555 is an apocalyptic number.

665820555 is a deficient number, since it is larger than the sum of its proper divisors (462158229).

665820555 is a wasteful number, since it uses less digits than its factorization.

665820555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2611086.

The product of its (nonzero) digits is 360000, while the sum is 42.

The square root of 665820555 is about 25803.4988906543. The cubic root of 665820555 is about 873.2107349643.

The spelling of 665820555 in words is "six hundred sixty-five million, eight hundred twenty thousand, five hundred fifty-five".