261643320 has 48 divisors (see below), whose sum is σ = 850341960. Its totient is φ = 69771456.

The previous prime is 261643309. The next prime is 261643321. The reversal of 261643320 is 23346162.

261643320 is a `hidden beast` number, since 2 + 616 + 43 + 3 + 2 + 0 = 666.

261643320 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261643321) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 363034 + ... + 363753.

Almost surely, 2^261643320 is an apocalyptic number.

261643320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261643320 is an abundant number, since it is smaller than the sum of its proper divisors (588698640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261643320 is a wasteful number, since it uses less digits than its factorization.

261643320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 726804 (or 726797 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 27.

The square root of 261643320 is about 16175.3924218240. The cubic root of 261643320 is about 639.5922858925.

Adding to 261643320 its reverse (23346162), we get a palindrome (284989482).

The spelling of 261643320 in words is "two hundred sixty-one million, six hundred forty-three thousand, three hundred twenty".