261826021 has 2 divisors, whose sum is σ = 261826022. Its totient is φ = 261826020.

The previous prime is 261826013. The next prime is 261826051. The reversal of 261826021 is 120628162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 136072225 + 125753796 = 11665^2 + 11214^2 .

It is a cyclic number.

It is not a de Polignac number, because 261826021 - 2³ = 261826013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261826051) 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 as a sum of consecutive naturals, namely, 130913010 + 130913011.

It is an arithmetic number, because the mean of its divisors is an integer number (130913011).

Almost surely, 2^261826021 is an apocalyptic number.

It is an amenable number.

261826021 is a deficient number, since it is larger than the sum of its proper divisors (1).

261826021 is an equidigital number, since it uses as much as digits as its factorization.

261826021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 261826021 is about 16181.0389345060. The cubic root of 261826021 is about 639.7411233272.

The spelling of 261826021 in words is "two hundred sixty-one million, eight hundred twenty-six thousand, twenty-one".