261219840 has 320 divisors, whose sum is σ = 985222656. Its totient is φ = 57802752.

The previous prime is 261219839. The next prime is 261219851. The reversal of 261219840 is 48912162.

It is a tau number, because it is divible by the number of its divisors (320).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2311624 + ... + 2311736.

Almost surely, 2^261219840 is an apocalyptic number.

261219840 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 261219840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (492611328).

261219840 is an abundant number, since it is smaller than the sum of its proper divisors (724002816).

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

261219840 is a wasteful number, since it uses less digits than its factorization.

261219840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189 (or 173 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 261219840 is about 16162.2968664729. The cubic root of 261219840 is about 639.2470311358.

The spelling of 261219840 in words is "two hundred sixty-one million, two hundred nineteen thousand, eight hundred forty".