660400655 has 4 divisors (see below), whose sum is σ = 792480792. Its totient is φ = 528320520.

The previous prime is 660400639. The next prime is 660400661. The reversal of 660400655 is 556004066.

660400655 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 660400655 - 2⁴ = 660400639 is a prime.

It is a super-2 number, since 2×660400655² = 872258050248858050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66040061 + ... + 66040070.

It is an arithmetic number, because the mean of its divisors is an integer number (198120198).

Almost surely, 2^660400655 is an apocalyptic number.

660400655 is a deficient number, since it is larger than the sum of its proper divisors (132080137).

660400655 is a wasteful number, since it uses less digits than its factorization.

660400655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132080136.

The product of its (nonzero) digits is 21600, while the sum is 32.

The square root of 660400655 is about 25698.2617116411. The cubic root of 660400655 is about 870.8349121608.

The spelling of 660400655 in words is "six hundred sixty million, four hundred thousand, six hundred fifty-five".