261662550 has 48 divisors (see below), whose sum is σ = 659584272. Its totient is φ = 68630400.

The previous prime is 261662549. The next prime is 261662573. The reversal of 261662550 is 55266162.

It is a happy number.

It is a congruent number.

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, 5149 + ... + 23448.

It is an arithmetic number, because the mean of its divisors is an integer number (13741339).

Almost surely, 2^261662550 is an apocalyptic number.

261662550 is an abundant number, since it is smaller than the sum of its proper divisors (397921722).

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

261662550 is a wasteful number, since it uses less digits than its factorization.

261662550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28673 (or 28668 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 33.

The square root of 261662550 is about 16175.9868323389. The cubic root of 261662550 is about 639.6079548807.

It can be divided in two parts, 26 and 1662550, that added together give a triangular number (1662576 = T₁₈₂₃).

The spelling of 261662550 in words is "two hundred sixty-one million, six hundred sixty-two thousand, five hundred fifty".