261551539 has 2 divisors, whose sum is σ = 261551540. Its totient is φ = 261551538.

The previous prime is 261551533. The next prime is 261551567. The reversal of 261551539 is 935155162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261551539 - 2⁹ = 261551027 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 261551498 and 261551507.

It is not a weakly prime, because it can be changed into another prime (261551533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130775769 + 130775770.

It is an arithmetic number, because the mean of its divisors is an integer number (130775770).

Almost surely, 2^261551539 is an apocalyptic number.

261551539 is a deficient number, since it is larger than the sum of its proper divisors (1).

261551539 is an equidigital number, since it uses as much as digits as its factorization.

261551539 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40500, while the sum is 37.

The square root of 261551539 is about 16172.5551166165. Note that the first 3 decimals coincide. The cubic root of 261551539 is about 639.5174903210.

It can be divided in two parts, 26155153 and 9, that added together give a palindrome (26155162).

The spelling of 261551539 in words is "two hundred sixty-one million, five hundred fifty-one thousand, five hundred thirty-nine".