261930989 has 2 divisors, whose sum is σ = 261930990. Its totient is φ = 261930988.

The previous prime is 261930973. The next prime is 261931009. The reversal of 261930989 is 989039162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 163584100 + 98346889 = 12790^2 + 9917^2 .

It is a cyclic number.

It is not a de Polignac number, because 261930989 - 2⁴ = 261930973 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261932989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130965494 + 130965495.

It is an arithmetic number, because the mean of its divisors is an integer number (130965495).

Almost surely, 2^261930989 is an apocalyptic number.

It is an amenable number.

261930989 is a deficient number, since it is larger than the sum of its proper divisors (1).

261930989 is an equidigital number, since it uses as much as digits as its factorization.

261930989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 209952, while the sum is 47.

The square root of 261930989 is about 16184.2821589343. The cubic root of 261930989 is about 639.8266042304.

The spelling of 261930989 in words is "two hundred sixty-one million, nine hundred thirty thousand, nine hundred eighty-nine".