261312481 has 4 divisors (see below), whose sum is σ = 261351364. Its totient is φ = 261273600.

The previous prime is 261312473. The next prime is 261312503. The reversal of 261312481 is 184213162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20566225 + 240746256 = 4535^2 + 15516^2 .

It is a cyclic number.

It is not a de Polignac number, because 261312481 - 2³ = 261312473 is a prime.

It is a super-2 number, since 2×261312481² = 136568425452750722, which contains 22 as substring.

It is a deceptive number, since it divides R_261312480.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261312421) 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 in 3 ways as a sum of consecutive naturals, for example, 6480 + ... + 23761.

It is an arithmetic number, because the mean of its divisors is an integer number (65337841).

It is a Poulet number, since it divides 2^261312480-1.

Almost surely, 2^261312481 is an apocalyptic number.

261312481 is the 8641-st nonagonal number.

It is an amenable number.

261312481 is a deficient number, since it is larger than the sum of its proper divisors (38883).

261312481 is an equidigital number, since it uses as much as digits as its factorization.

261312481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38882.

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

The square root of 261312481 is about 16165.1625726437. The cubic root of 261312481 is about 639.3225913546.

The spelling of 261312481 in words is "two hundred sixty-one million, three hundred twelve thousand, four hundred eighty-one".