261219920 has 90 divisors (see below), whose sum is σ = 662413518. Its totient is φ = 95756544.

The previous prime is 261219911. The next prime is 261219941. The reversal of 261219920 is 29912162.

261219920 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 3 ways, for example, as 1236544 + 259983376 = 1112^2 + 16124^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1879211 + ... + 1879349.

Almost surely, 2^261219920 is an apocalyptic number.

261219920 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 261219920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (331206759).

261219920 is an abundant number, since it is smaller than the sum of its proper divisors (401193598).

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

261219920 is a wasteful number, since it uses less digits than its factorization.

261219920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 317 (or 159 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 261219920 is about 16162.2993413685. The cubic root of 261219920 is about 639.2470963934.

The spelling of 261219920 in words is "two hundred sixty-one million, two hundred nineteen thousand, nine hundred twenty".