261005135389 has 2 divisors, whose sum is σ = 261005135390. Its totient is φ = 261005135388.

The previous prime is 261005135311. The next prime is 261005135411. The reversal of 261005135389 is 983531500162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 154069595289 + 106935540100 = 392517^2 + 327010^2 .

It is a cyclic number.

It is not a de Polignac number, because 261005135389 - 2²³ = 260996746781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261005138389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130502567694 + 130502567695.

It is an arithmetic number, because the mean of its divisors is an integer number (130502567695).

Almost surely, 2^261005135389 is an apocalyptic number.

It is an amenable number.

261005135389 is a deficient number, since it is larger than the sum of its proper divisors (1).

261005135389 is an equidigital number, since it uses as much as digits as its factorization.

261005135389 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 194400, while the sum is 43.

The spelling of 261005135389 in words is "two hundred sixty-one billion, five million, one hundred thirty-five thousand, three hundred eighty-nine".