261643650 has 48 divisors (see below), whose sum is σ = 666427584. Its totient is φ = 67884480.

The previous prime is 261643637. The next prime is 261643663. The reversal of 261643650 is 56346162.

261643650 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (261643637) and next prime (261643663).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18022 + ... + 29121.

It is an arithmetic number, because the mean of its divisors is an integer number (13883908).

Almost surely, 2^261643650 is an apocalyptic number.

261643650 is an abundant number, since it is smaller than the sum of its proper divisors (404783934).

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

261643650 is a wasteful number, since it uses less digits than its factorization.

261643650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47195 (or 47190 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 33.

The square root of 261643650 is about 16175.4026225006. The cubic root of 261643650 is about 639.5925547895.

The spelling of 261643650 in words is "two hundred sixty-one million, six hundred forty-three thousand, six hundred fifty".