261378778 has 8 divisors (see below), whose sum is σ = 398495700. Its totient is φ = 128546880.

The previous prime is 261378751. The next prime is 261378823. The reversal of 261378778 is 877873162.

It can be written as a sum of positive squares in 2 ways, for example, as 261371889 + 6889 = 16167^2 + 83^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1071103 + ... + 1071346.

Almost surely, 2^261378778 is an apocalyptic number.

261378778 is a deficient number, since it is larger than the sum of its proper divisors (137116922).

261378778 is a wasteful number, since it uses less digits than its factorization.

261378778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2142512.

The product of its digits is 790272, while the sum is 49.

The square root of 261378778 is about 16167.2130560589. The cubic root of 261378778 is about 639.3766538136.

The spelling of 261378778 in words is "two hundred sixty-one million, three hundred seventy-eight thousand, seven hundred seventy-eight".