261339556 has 27 divisors (see below), whose sum is σ = 468647809. Its totient is φ = 127517408.

The previous prime is 261339523. The next prime is 261339571. The reversal of 261339556 is 655933162.

It is a happy number.

The square root of 261339556 is 16166.

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

261339556 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 153512100 + 107827456 = 12390^2 + 10384^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1907520 + ... + 1907656.

Almost surely, 2^261339556 is an apocalyptic number.

261339556 is the 16166-th square number.

It is an amenable number.

261339556 is a deficient number, since it is larger than the sum of its proper divisors (207308253).

261339556 is an equidigital number, since it uses as much as digits as its factorization.

261339556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 396 (or 198 counting only the distinct ones).

The product of its digits is 145800, while the sum is 40.

The cubic root of 261339556 is about 639.3446710008.

The spelling of 261339556 in words is "two hundred sixty-one million, three hundred thirty-nine thousand, five hundred fifty-six".