261191888 has 20 divisors (see below), whose sum is σ = 507046788. Its totient is φ = 130341120.

The previous prime is 261191881. The next prime is 261191911. The reversal of 261191888 is 888191162.

261191888 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 198021184 + 63170704 = 14072^2 + 7948^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261191881) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7331 + ... + 24002.

Almost surely, 2^261191888 is an apocalyptic number.

It is an amenable number.

261191888 is a deficient number, since it is larger than the sum of its proper divisors (245854900).

261191888 is a wasteful number, since it uses less digits than its factorization.

261191888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31862 (or 31856 counting only the distinct ones).

The product of its digits is 55296, while the sum is 44.

The square root of 261191888 is about 16161.4321147601. The cubic root of 261191888 is about 639.2242293068.

The spelling of 261191888 in words is "two hundred sixty-one million, one hundred ninety-one thousand, eight hundred eighty-eight".