261616563 has 48 divisors (see below), whose sum is σ = 416576160. Its totient is φ = 158184000.

The previous prime is 261616543. The next prime is 261616609. The reversal of 261616563 is 365616162.

It is not a de Polignac number, because 261616563 - 2¹² = 261612467 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261616543) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1997008 + ... + 1997138.

It is an arithmetic number, because the mean of its divisors is an integer number (8678670).

Almost surely, 2^261616563 is an apocalyptic number.

261616563 is a deficient number, since it is larger than the sum of its proper divisors (154959597).

261616563 is a wasteful number, since it uses less digits than its factorization.

261616563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277 (or 248 counting only the distinct ones).

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

The square root of 261616563 is about 16174.5653110060. The cubic root of 261616563 is about 639.5704824768.

The spelling of 261616563 in words is "two hundred sixty-one million, six hundred sixteen thousand, five hundred sixty-three".