261663064 has 64 divisors (see below), whose sum is σ = 549239040. Its totient is φ = 116052480.

The previous prime is 261663049. The next prime is 261663091. The reversal of 261663064 is 460366162.

261663064 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 an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 892902 + ... + 893194.

It is an arithmetic number, because the mean of its divisors is an integer number (8581860).

Almost surely, 2^261663064 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261663064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (274619520).

261663064 is an abundant number, since it is smaller than the sum of its proper divisors (287575976).

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

261663064 is a wasteful number, since it uses less digits than its factorization.

261663064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 620 (or 616 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 34.

The square root of 261663064 is about 16176.0027200789. The cubic root of 261663064 is about 639.6083736877.

The spelling of 261663064 in words is "two hundred sixty-one million, six hundred sixty-three thousand, sixty-four".