261450640 has 120 divisors (see below), whose sum is σ = 700723008. Its totient is φ = 89959680.

The previous prime is 261450619. The next prime is 261450641. The reversal of 261450640 is 46054162.

It is a junction number, because it is equal to n+sod(n) for n = 261450599 and 261450608.

It is not an unprimeable number, because it can be changed into a prime (261450641) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 317269 + ... + 318091.

Almost surely, 2^261450640 is an apocalyptic number.

261450640 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 261450640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (350361504).

261450640 is an abundant number, since it is smaller than the sum of its proper divisors (439272368).

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

261450640 is a wasteful number, since it uses less digits than its factorization.

261450640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 885 (or 860 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 261450640 is about 16169.4353642915. The cubic root of 261450640 is about 639.4352439757.

The spelling of 261450640 in words is "two hundred sixty-one million, four hundred fifty thousand, six hundred forty".