261643330 has 16 divisors (see below), whose sum is σ = 507185784. Its totient is φ = 96606720.

The previous prime is 261643321. The next prime is 261643363. The reversal of 261643330 is 33346162.

It can be written as a sum of positive squares in 4 ways, for example, as 201441249 + 60202081 = 14193^2 + 7759^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1006191 + ... + 1006450.

Almost surely, 2^261643330 is an apocalyptic number.

261643330 is a deficient number, since it is larger than the sum of its proper divisors (245542454).

261643330 is a wasteful number, since it uses less digits than its factorization.

261643330 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2012661.

The product of its (nonzero) digits is 7776, while the sum is 28.

The square root of 261643330 is about 16175.3927309355. The cubic root of 261643330 is about 639.5922940409.

Adding to 261643330 its reverse (33346162), we get a palindrome (294989492).

The spelling of 261643330 in words is "two hundred sixty-one million, six hundred forty-three thousand, three hundred thirty".