261840040 has 128 divisors (see below), whose sum is σ = 740689920. Its totient is φ = 80928000.

The previous prime is 261840031. The next prime is 261840071. The reversal of 261840040 is 40048162.

It is a junction number, because it is equal to n+sod(n) for n = 261839987 and 261840014.

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, 464799 + ... + 465361.

It is an arithmetic number, because the mean of its divisors is an integer number (5786640).

Almost surely, 2^261840040 is an apocalyptic number.

261840040 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 261840040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (370344960).

261840040 is an abundant number, since it is smaller than the sum of its proper divisors (478849880).

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

261840040 is a wasteful number, since it uses less digits than its factorization.

261840040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 743 (or 739 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 25.

The square root of 261840040 is about 16181.4721209166. The cubic root of 261840040 is about 639.7525410499.

The spelling of 261840040 in words is "two hundred sixty-one million, eight hundred forty thousand, forty".