261078266 has 4 divisors (see below), whose sum is σ = 391617402. Its totient is φ = 130539132.

The previous prime is 261078263. The next prime is 261078287. The reversal of 261078266 is 662870162.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 662870162 = 2 ⋅331435081.

It can be written as a sum of positive squares in only one way, i.e., 258534241 + 2544025 = 16079^2 + 1595^2 .

It is not an unprimeable number, because it can be changed into a prime (261078263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65269565 + ... + 65269568.

Almost surely, 2^261078266 is an apocalyptic number.

261078266 is a deficient number, since it is larger than the sum of its proper divisors (130539136).

261078266 is a wasteful number, since it uses less digits than its factorization.

261078266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130539135.

The product of its (nonzero) digits is 48384, while the sum is 38.

The square root of 261078266 is about 16157.9165117289. The cubic root of 261078266 is about 639.1315254711.

The spelling of 261078266 in words is "two hundred sixty-one million, seventy-eight thousand, two hundred sixty-six".