261263290 has 16 divisors (see below), whose sum is σ = 482984712. Its totient is φ = 101680704.

The previous prime is 261263287. The next prime is 261263297. The reversal of 261263290 is 92362162.

It can be written as a sum of positive squares in 4 ways, for example, as 255392361 + 5870929 = 15981^2 + 2423^2 .

It is not an unprimeable number, because it can be changed into a prime (261263297) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 352689 + ... + 353428.

Almost surely, 2^261263290 is an apocalyptic number.

261263290 is a deficient number, since it is larger than the sum of its proper divisors (221721422).

261263290 is a wasteful number, since it uses less digits than its factorization.

261263290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 706161.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 261263290 is about 16163.6409883417. The cubic root of 261263290 is about 639.2824722208.

The spelling of 261263290 in words is "two hundred sixty-one million, two hundred sixty-three thousand, two hundred ninety".