261815878 has 8 divisors (see below), whose sum is σ = 415825272. Its totient is φ = 123207456.

The previous prime is 261815867. The next prime is 261815891. The reversal of 261815878 is 878518162.

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

It is a congruent number.

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, 3850200 + ... + 3850267.

It is an arithmetic number, because the mean of its divisors is an integer number (51978159).

Almost surely, 2^261815878 is an apocalyptic number.

261815878 is a deficient number, since it is larger than the sum of its proper divisors (154009394).

261815878 is a wasteful number, since it uses less digits than its factorization.

261815878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7700486.

The product of its digits is 215040, while the sum is 46.

The square root of 261815878 is about 16180.7255090741. The cubic root of 261815878 is about 639.7328621442.

It can be divided in two parts, 2618 and 15878, that added together give a square (18496 = 136²).

The spelling of 261815878 in words is "two hundred sixty-one million, eight hundred fifteen thousand, eight hundred seventy-eight".