261243761 has 4 divisors (see below), whose sum is σ = 262907892. Its totient is φ = 259579632.

The previous prime is 261243707. The next prime is 261243767. The reversal of 261243761 is 167342162.

261243761 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 175403536 + 85840225 = 13244^2 + 9265^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261243761 is a prime.

It is a super-2 number, since 2×261243761² = 136496605322850242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261243767) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 831830 + ... + 832143.

It is an arithmetic number, because the mean of its divisors is an integer number (65726973).

Almost surely, 2^261243761 is an apocalyptic number.

It is an amenable number.

261243761 is a deficient number, since it is larger than the sum of its proper divisors (1664131).

261243761 is a wasteful number, since it uses less digits than its factorization.

261243761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1664130.

The product of its digits is 12096, while the sum is 32.

The square root of 261243761 is about 16163.0368743006. The cubic root of 261243761 is about 639.2665433871.

The spelling of 261243761 in words is "two hundred sixty-one million, two hundred forty-three thousand, seven hundred sixty-one".