261155815 has 16 divisors (see below), whose sum is σ = 319472640. Its totient is φ = 204906240.

The previous prime is 261155789. The next prime is 261155831. The reversal of 261155815 is 518551162.

It is not a de Polignac number, because 261155815 - 2⁹ = 261155303 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 54205 + ... + 58825.

It is an arithmetic number, because the mean of its divisors is an integer number (19967040).

Almost surely, 2^261155815 is an apocalyptic number.

261155815 is a deficient number, since it is larger than the sum of its proper divisors (58316825).

261155815 is a wasteful number, since it uses less digits than its factorization.

261155815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4842.

The product of its digits is 12000, while the sum is 34.

The square root of 261155815 is about 16160.3160550776. The cubic root of 261155815 is about 639.1948003718.

The spelling of 261155815 in words is "two hundred sixty-one million, one hundred fifty-five thousand, eight hundred fifteen".