261504546421 has 2 divisors, whose sum is σ = 261504546422. Its totient is φ = 261504546420.

The previous prime is 261504546403. The next prime is 261504546463. The reversal of 261504546421 is 124645405162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 260468350321 + 1036196100 = 510361^2 + 32190^2 .

It is a cyclic number.

It is not a de Polignac number, because 261504546421 - 2²⁷ = 261370328693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261504546481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130752273210 + 130752273211.

It is an arithmetic number, because the mean of its divisors is an integer number (130752273211).

Almost surely, 2^261504546421 is an apocalyptic number.

It is an amenable number.

261504546421 is a deficient number, since it is larger than the sum of its proper divisors (1).

261504546421 is an equidigital number, since it uses as much as digits as its factorization.

261504546421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 230400, while the sum is 40.

The spelling of 261504546421 in words is "two hundred sixty-one billion, five hundred four million, five hundred forty-six thousand, four hundred twenty-one".