261660361 has 2 divisors, whose sum is σ = 261660362. Its totient is φ = 261660360.

The previous prime is 261660349. The next prime is 261660389. The reversal of 261660361 is 163066162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 160275600 + 101384761 = 12660^2 + 10069^2 .

It is a cyclic number.

It is not a de Polignac number, because 261660361 - 2¹³ = 261652169 is a prime.

It is a super-2 number, since 2×261660361² = 136932289037300642, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (261660331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130830180 + 130830181.

It is an arithmetic number, because the mean of its divisors is an integer number (130830181).

Almost surely, 2^261660361 is an apocalyptic number.

It is an amenable number.

261660361 is a deficient number, since it is larger than the sum of its proper divisors (1).

261660361 is an equidigital number, since it uses as much as digits as its factorization.

261660361 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 261660361 is about 16175.9191701739. The cubic root of 261660361 is about 639.6061712785.

The spelling of 261660361 in words is "two hundred sixty-one million, six hundred sixty thousand, three hundred sixty-one".