261396761 has 4 divisors (see below), whose sum is σ = 262841124. Its totient is φ = 259952400.

The previous prime is 261396703. The next prime is 261396767. The reversal of 261396761 is 167693162.

261396761 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 58049161 + 203347600 = 7619^2 + 14260^2 .

It is a cyclic number.

It is not a de Polignac number, because 261396761 - 2⁶ = 261396697 is a prime.

It is a super-2 number, since 2×261396761² = 136656533322582242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261396767) 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, 721910 + ... + 722271.

It is an arithmetic number, because the mean of its divisors is an integer number (65710281).

Almost surely, 2^261396761 is an apocalyptic number.

It is an amenable number.

261396761 is a deficient number, since it is larger than the sum of its proper divisors (1444363).

261396761 is a wasteful number, since it uses less digits than its factorization.

261396761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1444362.

The product of its digits is 81648, while the sum is 41.

The square root of 261396761 is about 16167.7692029544. The cubic root of 261396761 is about 639.3913166294.

The spelling of 261396761 in words is "two hundred sixty-one million, three hundred ninety-six thousand, seven hundred sixty-one".