261563616 has 72 divisors (see below), whose sum is σ = 767841984. Its totient is φ = 84372480.

The previous prime is 261563611. The next prime is 261563623. The reversal of 261563616 is 616365162.

261563616 is a `hidden beast` number, since 2 + 6 + 1 + 5 + 636 + 16 = 666.

261563616 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261563611) 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, 5721 + ... + 23576.

It is an arithmetic number, because the mean of its divisors is an integer number (10664472).

Almost surely, 2^261563616 is an apocalyptic number.

It is an amenable number.

261563616 is an abundant number, since it is smaller than the sum of its proper divisors (506278368).

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

261563616 is a wasteful number, since it uses less digits than its factorization.

261563616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29344 (or 29333 counting only the distinct ones).

The product of its digits is 38880, while the sum is 36.

The square root of 261563616 is about 16172.9284917729. The cubic root of 261563616 is about 639.5273332935.

The spelling of 261563616 in words is "two hundred sixty-one million, five hundred sixty-three thousand, six hundred sixteen".