261521206 has 32 divisors (see below), whose sum is σ = 425426400. Its totient is φ = 120165120.

The previous prime is 261521191. The next prime is 261521231. The reversal of 261521206 is 602125162.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 356416 + ... + 357148.

It is an arithmetic number, because the mean of its divisors is an integer number (13294575).

Almost surely, 2^261521206 is an apocalyptic number.

261521206 is a deficient number, since it is larger than the sum of its proper divisors (163905194).

261521206 is a wasteful number, since it uses less digits than its factorization.

261521206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1024.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 261521206 is about 16171.6172969805. The cubic root of 261521206 is about 639.4927670433.

Adding to 261521206 its reverse (602125162), we get a palindrome (863646368).

The spelling of 261521206 in words is "two hundred sixty-one million, five hundred twenty-one thousand, two hundred six".