261321547 has 2 divisors, whose sum is σ = 261321548. Its totient is φ = 261321546.

The previous prime is 261321503. The next prime is 261321553. The reversal of 261321547 is 745123162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261321547 - 2⁷ = 261321419 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (261321587) 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, 130660773 + 130660774.

It is an arithmetic number, because the mean of its divisors is an integer number (130660774).

Almost surely, 2^261321547 is an apocalyptic number.

261321547 is a deficient number, since it is larger than the sum of its proper divisors (1).

261321547 is an equidigital number, since it uses as much as digits as its factorization.

261321547 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10080, while the sum is 31.

The square root of 261321547 is about 16165.4429880533. The cubic root of 261321547 is about 639.3299848419.

The spelling of 261321547 in words is "two hundred sixty-one million, three hundred twenty-one thousand, five hundred forty-seven".