261477989 has 2 divisors, whose sum is σ = 261477990. Its totient is φ = 261477988.

The previous prime is 261477977. The next prime is 261478067. The reversal of 261477989 is 989774162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 231557089 + 29920900 = 15217^2 + 5470^2 .

It is a cyclic number.

It is not a de Polignac number, because 261477989 - 2⁴ = 261477973 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261477989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261467989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130738994 + 130738995.

It is an arithmetic number, because the mean of its divisors is an integer number (130738995).

Almost surely, 2^261477989 is an apocalyptic number.

It is an amenable number.

261477989 is a deficient number, since it is larger than the sum of its proper divisors (1).

261477989 is an equidigital number, since it uses as much as digits as its factorization.

261477989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1524096, while the sum is 53.

The square root of 261477989 is about 16170.2810427030. The cubic root of 261477989 is about 639.4575392035.

The spelling of 261477989 in words is "two hundred sixty-one million, four hundred seventy-seven thousand, nine hundred eighty-nine".