255566621 has 4 divisors (see below), whose sum is σ = 255642492. Its totient is φ = 255490752.

The previous prime is 255566617. The next prime is 255566629. The reversal of 255566621 is 126665552.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 144264121 + 111302500 = 12011^2 + 10550^2 .

It is a cyclic number.

It is not a de Polignac number, because 255566621 - 2² = 255566617 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (255566629) 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 3 ways as a sum of consecutive naturals, for example, 32636 + ... + 39701.

It is an arithmetic number, because the mean of its divisors is an integer number (63910623).

Almost surely, 2^255566621 is an apocalyptic number.

It is an amenable number.

255566621 is a deficient number, since it is larger than the sum of its proper divisors (75871).

255566621 is an equidigital number, since it uses as much as digits as its factorization.

255566621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75870.

The product of its digits is 108000, while the sum is 38.

The square root of 255566621 is about 15986.4511696624. The cubic root of 255566621 is about 634.6019130524.

The spelling of 255566621 in words is "two hundred fifty-five million, five hundred sixty-six thousand, six hundred twenty-one".