261770161 has 2 divisors, whose sum is σ = 261770162. Its totient is φ = 261770160.

The previous prime is 261770123. The next prime is 261770209. The reversal of 261770161 is 161077162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 233478400 + 28291761 = 15280^2 + 5319^2 .

It is a cyclic number.

It is not a de Polignac number, because 261770161 - 2²¹ = 259673009 is a prime.

It is not a weakly prime, because it can be changed into another prime (261770101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130885080 + 130885081.

It is an arithmetic number, because the mean of its divisors is an integer number (130885081).

Almost surely, 2^261770161 is an apocalyptic number.

It is an amenable number.

261770161 is a deficient number, since it is larger than the sum of its proper divisors (1).

261770161 is an equidigital number, since it uses as much as digits as its factorization.

261770161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3528, while the sum is 31.

The square root of 261770161 is about 16179.3127480743. The cubic root of 261770161 is about 639.6956243088.

The spelling of 261770161 in words is "two hundred sixty-one million, seven hundred seventy thousand, one hundred sixty-one".