261889489 has 3 divisors (see below), whose sum is σ = 261905673. Its totient is φ = 261873306.

The previous prime is 261889487. The next prime is 261889493. The reversal of 261889489 is 984988162.

The square root of 261889489 is 16183.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 984988162 = 2 ⋅492494081.

It is not a de Polignac number, because 261889489 - 2¹ = 261889487 is a prime.

It is a super-2 number, since 2×261889489² = 137172208897362242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261889487) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 8092 + ... + 24274.

It is an arithmetic number, because the mean of its divisors is an integer number (87301891).

Almost surely, 2^261889489 is an apocalyptic number.

261889489 is the 16183-rd square number.

261889489 is the 8092-nd centered octagonal number.

It is an amenable number.

261889489 is a deficient number, since it is larger than the sum of its proper divisors (16184).

261889489 is an frugal number, since it uses more digits than its factorization.

261889489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32366 (or 16183 counting only the distinct ones).

The product of its digits is 1990656, while the sum is 55.

The cubic root of 261889489 is about 639.7928113516.

The spelling of 261889489 in words is "two hundred sixty-one million, eight hundred eighty-nine thousand, four hundred eighty-nine".