261822978 has 12 divisors (see below), whose sum is σ = 567283158. Its totient is φ = 87274320.

The previous prime is 261822971. The next prime is 261823039. The reversal of 261822978 is 879228162.

261822978 is a `hidden beast` number, since 2 + 618 + 2 + 29 + 7 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 261565929 + 257049 = 16173^2 + 507^2 .

It is not an unprimeable number, because it can be changed into a prime (261822971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7272843 + ... + 7272878.

Almost surely, 2^261822978 is an apocalyptic number.

261822978 is an abundant number, since it is smaller than the sum of its proper divisors (305460180).

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

261822978 is a wasteful number, since it uses less digits than its factorization.

261822978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14545729 (or 14545726 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 261822978 is about 16180.9449044238. The cubic root of 261822978 is about 639.7386449133.

The spelling of 261822978 in words is "two hundred sixty-one million, eight hundred twenty-two thousand, nine hundred seventy-eight".