261551660 has 12 divisors (see below), whose sum is σ = 549258528. Its totient is φ = 104620656.

The previous prime is 261551617. The next prime is 261551677. The reversal of 261551660 is 66155162.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 6538772 + ... + 6538811.

It is an arithmetic number, because the mean of its divisors is an integer number (45771544).

Almost surely, 2^261551660 is an apocalyptic number.

261551660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261551660 is an abundant number, since it is smaller than the sum of its proper divisors (287706868).

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

261551660 is a wasteful number, since it uses less digits than its factorization.

261551660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13077592 (or 13077590 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 32.

The square root of 261551660 is about 16172.5588575216. The cubic root of 261551660 is about 639.5175889396.

The spelling of 261551660 in words is "two hundred sixty-one million, five hundred fifty-one thousand, six hundred sixty".