261012161 has 2 divisors, whose sum is σ = 261012162. Its totient is φ = 261012160.

The previous prime is 261012137. The next prime is 261012173. The reversal of 261012161 is 161210162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 230098561 + 30913600 = 15169^2 + 5560^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261012161 is a prime.

It is not a weakly prime, because it can be changed into another prime (261012131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130506080 + 130506081.

It is an arithmetic number, because the mean of its divisors is an integer number (130506081).

Almost surely, 2^261012161 is an apocalyptic number.

It is an amenable number.

261012161 is a deficient number, since it is larger than the sum of its proper divisors (1).

261012161 is an equidigital number, since it uses as much as digits as its factorization.

261012161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 261012161 is about 16155.8707905207. The cubic root of 261012161 is about 639.0775782308.

The spelling of 261012161 in words is "two hundred sixty-one million, twelve thousand, one hundred sixty-one".