261870840 has 512 divisors, whose sum is σ = 1128038400. Its totient is φ = 52462080.

The previous prime is 261870821. The next prime is 261870853. The reversal of 261870840 is 48078162.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 261870795 and 261870804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 3908487 + ... + 3908553.

It is an arithmetic number, because the mean of its divisors is an integer number (2203200).

Almost surely, 2^261870840 is an apocalyptic number.

261870840 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 261870840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (564019200).

261870840 is an abundant number, since it is smaller than the sum of its proper divisors (866167560).

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

261870840 is a wasteful number, since it uses less digits than its factorization.

261870840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152 (or 142 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 261870840 is about 16182.4237986774. The cubic root of 261870840 is about 639.7776245649. Note that the first 3 decimals are identical.

The spelling of 261870840 in words is "two hundred sixty-one million, eight hundred seventy thousand, eight hundred forty".