261291101 has 2 divisors, whose sum is σ = 261291102. Its totient is φ = 261291100.

The previous prime is 261291067. The next prime is 261291127. The reversal of 261291101 is 101192162.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 260047876 + 1243225 = 16126^2 + 1115^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261291101 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261291161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130645550 + 130645551.

It is an arithmetic number, because the mean of its divisors is an integer number (130645551).

Almost surely, 2^261291101 is an apocalyptic number.

It is an amenable number.

261291101 is a deficient number, since it is larger than the sum of its proper divisors (1).

261291101 is an equidigital number, since it uses as much as digits as its factorization.

261291101 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 23.

The square root of 261291101 is about 16164.5012604782. The cubic root of 261291101 is about 639.3051548998.

The spelling of 261291101 in words is "two hundred sixty-one million, two hundred ninety-one thousand, one hundred one".