255521621 has 2 divisors, whose sum is σ = 255521622. Its totient is φ = 255521620.

The previous prime is 255521573. The next prime is 255521627. The reversal of 255521621 is 126125552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 194463025 + 61058596 = 13945^2 + 7814^2 .

It is a cyclic number.

It is not a de Polignac number, because 255521621 - 2¹⁰ = 255520597 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (255521627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 127760810 + 127760811.

It is an arithmetic number, because the mean of its divisors is an integer number (127760811).

Almost surely, 2^255521621 is an apocalyptic number.

It is an amenable number.

255521621 is a deficient number, since it is larger than the sum of its proper divisors (1).

255521621 is an equidigital number, since it uses as much as digits as its factorization.

255521621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6000, while the sum is 29.

The square root of 255521621 is about 15985.0436658772. The cubic root of 255521621 is about 634.5646641056.

The spelling of 255521621 in words is "two hundred fifty-five million, five hundred twenty-one thousand, six hundred twenty-one".