261861437 has 2 divisors, whose sum is σ = 261861438. Its totient is φ = 261861436.

The previous prime is 261861409. The next prime is 261861451. The reversal of 261861437 is 734168162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 221741881 + 40119556 = 14891^2 + 6334^2 .

It is a cyclic number.

It is not a de Polignac number, because 261861437 - 2²⁶ = 194752573 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261861437.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261861497) 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, 130930718 + 130930719.

It is an arithmetic number, because the mean of its divisors is an integer number (130930719).

Almost surely, 2^261861437 is an apocalyptic number.

It is an amenable number.

261861437 is a deficient number, since it is larger than the sum of its proper divisors (1).

261861437 is an equidigital number, since it uses as much as digits as its factorization.

261861437 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48384, while the sum is 38.

The square root of 261861437 is about 16182.1332648078. The cubic root of 261861437 is about 639.7699669718.

The spelling of 261861437 in words is "two hundred sixty-one million, eight hundred sixty-one thousand, four hundred thirty-seven".