261889493 has 2 divisors, whose sum is σ = 261889494. Its totient is φ = 261889492.

The previous prime is 261889487. The next prime is 261889501. The reversal of 261889493 is 394988162.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 261889489 + 4 = 16183^2 + 2^2 .

It is a cyclic number.

It is not a de Polignac number, because 261889493 - 2⁸ = 261889237 is a prime.

It is a super-2 number, since 2×261889493² = 137172213087594098, which contains 22 as substring.

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 (261889093) 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, 130944746 + 130944747.

It is an arithmetic number, because the mean of its divisors is an integer number (130944747).

Almost surely, 2^261889493 is an apocalyptic number.

It is an amenable number.

261889493 is a deficient number, since it is larger than the sum of its proper divisors (1).

261889493 is an equidigital number, since it uses as much as digits as its factorization.

261889493 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 746496, while the sum is 50.

The square root of 261889493 is about 16183.0001235865. Note that the first 3 decimals coincide. The cubic root of 261889493 is about 639.7928146089.

The spelling of 261889493 in words is "two hundred sixty-one million, eight hundred eighty-nine thousand, four hundred ninety-three".