261561338 has 8 divisors (see below), whose sum is σ = 392436660. Its totient is φ = 130749120.

The previous prime is 261561323. The next prime is 261561347. The reversal of 261561338 is 833165162.

It can be written as a sum of positive squares in 2 ways, for example, as 259757689 + 1803649 = 16117^2 + 1343^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 261561298 and 261561307.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3503 + ... + 23138.

Almost surely, 2^261561338 is an apocalyptic number.

261561338 is a deficient number, since it is larger than the sum of its proper divisors (130875322).

261561338 is a wasteful number, since it uses less digits than its factorization.

261561338 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31552.

The product of its digits is 25920, while the sum is 35.

The square root of 261561338 is about 16172.8580652895. The cubic root of 261561338 is about 639.5254767057.

The spelling of 261561338 in words is "two hundred sixty-one million, five hundred sixty-one thousand, three hundred thirty-eight".