661812255 has 64 divisors (see below), whose sum is σ = 1271424000. Its totient is φ = 324694656.

The previous prime is 661812209. The next prime is 661812259. The reversal of 661812255 is 552218166.

661812255 is a `hidden beast` number, since 6 + 618 + 12 + 25 + 5 = 666.

It is not a de Polignac number, because 661812255 - 2⁶ = 661812191 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661812259) by changing a digit.

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 63 ways as a sum of consecutive naturals, for example, 770016 + ... + 770874.

It is an arithmetic number, because the mean of its divisors is an integer number (19866000).

Almost surely, 2^661812255 is an apocalyptic number.

661812255 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

661812255 is a deficient number, since it is larger than the sum of its proper divisors (609611745).

661812255 is a wasteful number, since it uses less digits than its factorization.

661812255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1325 (or 1319 counting only the distinct ones).

The product of its digits is 28800, while the sum is 36.

The square root of 661812255 is about 25725.7119435012. The cubic root of 661812255 is about 871.4549376660.

The spelling of 661812255 in words is "six hundred sixty-one million, eight hundred twelve thousand, two hundred fifty-five".