261232781 has 4 divisors (see below), whose sum is σ = 272590752. Its totient is φ = 249874812.

The previous prime is 261232759. The next prime is 261232787. The reversal of 261232781 is 187232162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 261232781 - 2¹⁰ = 261231757 is a prime.

It is a super-2 number, since 2×261232781² = 136485131737987922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261232787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5678951 + ... + 5678996.

It is an arithmetic number, because the mean of its divisors is an integer number (68147688).

Almost surely, 2^261232781 is an apocalyptic number.

It is an amenable number.

261232781 is a deficient number, since it is larger than the sum of its proper divisors (11357971).

261232781 is a wasteful number, since it uses less digits than its factorization.

261232781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11357970.

The product of its digits is 8064, while the sum is 32.

The square root of 261232781 is about 16162.6972068402. The cubic root of 261232781 is about 639.2575871987.

The spelling of 261232781 in words is "two hundred sixty-one million, two hundred thirty-two thousand, seven hundred eighty-one".