261691600 has 30 divisors (see below), whose sum is σ = 628715030. Its totient is φ = 104676480.

The previous prime is 261691589. The next prime is 261691637. The reversal of 261691600 is 6196162.

It can be written as a sum of positive squares in 3 ways, for example, as 63107136 + 198584464 = 7944^2 + 14092^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 326715 + ... + 327514.

Almost surely, 2^261691600 is an apocalyptic number.

261691600 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261691600 is an abundant number, since it is smaller than the sum of its proper divisors (367023430).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261691600 is a wasteful number, since it uses less digits than its factorization.

261691600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 654247 (or 654236 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 261691600 is about 16176.8847433614. The cubic root of 261691600 is about 639.6316239455.

The spelling of 261691600 in words is "two hundred sixty-one million, six hundred ninety-one thousand, six hundred".