255631021 has 2 divisors, whose sum is σ = 255631022. Its totient is φ = 255631020.

The previous prime is 255631007. The next prime is 255631049. The reversal of 255631021 is 120136552.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 233172900 + 22458121 = 15270^2 + 4739^2 .

It is a cyclic number.

It is not a de Polignac number, because 255631021 - 2¹⁷ = 255499949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (255631081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 127815510 + 127815511.

It is an arithmetic number, because the mean of its divisors is an integer number (127815511).

Almost surely, 2^255631021 is an apocalyptic number.

It is an amenable number.

255631021 is a deficient number, since it is larger than the sum of its proper divisors (1).

255631021 is an equidigital number, since it uses as much as digits as its factorization.

255631021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 255631021 is about 15988.4652484221. The cubic root of 255631021 is about 634.6552128283.

Adding to 255631021 its reverse (120136552), we get a palindrome (375767573).

The spelling of 255631021 in words is "two hundred fifty-five million, six hundred thirty-one thousand, twenty-one".