261905663 has 8 divisors (see below), whose sum is σ = 269302320. Its totient is φ = 254557120.

The previous prime is 261905659. The next prime is 261905681. The reversal of 261905663 is 366509162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 261905663 - 2² = 261905659 is a prime.

It is a super-2 number, since 2×261905663² = 137189152622939138, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261905603) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 845 + ... + 22902.

It is an arithmetic number, because the mean of its divisors is an integer number (33662790).

Almost surely, 2^261905663 is an apocalyptic number.

261905663 is a deficient number, since it is larger than the sum of its proper divisors (7396657).

261905663 is a wasteful number, since it uses less digits than its factorization.

261905663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24057.

The product of its (nonzero) digits is 58320, while the sum is 38.

The square root of 261905663 is about 16183.4997142151. The cubic root of 261905663 is about 639.8059820417.

The spelling of 261905663 in words is "two hundred sixty-one million, nine hundred five thousand, six hundred sixty-three".