261869840 has 40 divisors (see below), whose sum is σ = 612282240. Its totient is φ = 104157056.

The previous prime is 261869827. The next prime is 261869857. The reversal of 261869840 is 48968162.

It is a happy number.

261869840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 261869791 and 261869800.

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, 5177 + ... + 23463.

It is an arithmetic number, because the mean of its divisors is an integer number (15307056).

Almost surely, 2^261869840 is an apocalyptic number.

261869840 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 261869840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (306141120).

261869840 is an abundant number, since it is smaller than the sum of its proper divisors (350412400).

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

261869840 is a wasteful number, since it uses less digits than its factorization.

261869840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18479 (or 18473 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 44.

The square root of 261869840 is about 16182.3929009278. The cubic root of 261869840 is about 639.7768101960.

The spelling of 261869840 in words is "two hundred sixty-one million, eight hundred sixty-nine thousand, eight hundred forty".