261388863 has 20 divisors (see below), whose sum is σ = 391343040. Its totient is φ = 173869632.

The previous prime is 261388849. The next prime is 261388877. The reversal of 261388863 is 368883162.

261388863 is a `hidden beast` number, since 261 + 388 + 8 + 6 + 3 = 666.

It is an interprime number because it is at equal distance from previous prime (261388849) and next prime (261388877).

It is not a de Polignac number, because 261388863 - 2⁴ = 261388847 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261388823) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 35431 + ... + 42167.

It is an arithmetic number, because the mean of its divisors is an integer number (19567152).

Almost surely, 2^261388863 is an apocalyptic number.

261388863 is a deficient number, since it is larger than the sum of its proper divisors (129954177).

261388863 is an equidigital number, since it uses as much as digits as its factorization.

261388863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7228 (or 7219 counting only the distinct ones).

The product of its digits is 331776, while the sum is 45.

The square root of 261388863 is about 16167.5249497256. The cubic root of 261388863 is about 639.3848769125.

The spelling of 261388863 in words is "two hundred sixty-one million, three hundred eighty-eight thousand, eight hundred sixty-three".