261621760 has 96 divisors (see below), whose sum is σ = 650122200. Its totient is φ = 100925440.

The previous prime is 261621749. The next prime is 261621793. The reversal of 261621760 is 67126162.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 171295744 + 90326016 = 13088^2 + 9504^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 296520 + ... + 297400.

Almost surely, 2^261621760 is an apocalyptic number.

261621760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261621760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (325061100).

261621760 is an abundant number, since it is smaller than the sum of its proper divisors (388500440).

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

261621760 is an equidigital number, since it uses as much as digits as its factorization.

261621760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 937 (or 917 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 31.

The square root of 261621760 is about 16174.7259636756. The cubic root of 261621760 is about 639.5747174607.

The spelling of 261621760 in words is "two hundred sixty-one million, six hundred twenty-one thousand, seven hundred sixty".