261664040 has 64 divisors (see below), whose sum is σ = 655983360. Its totient is φ = 93118720.

The previous prime is 261664019. The next prime is 261664049. The reversal of 261664040 is 40466162.

261664040 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 261663994 and 261664012.

It is not an unprimeable number, because it can be changed into a prime (261664049) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14354 + ... + 27006.

It is an arithmetic number, because the mean of its divisors is an integer number (10249740).

Almost surely, 2^261664040 is an apocalyptic number.

261664040 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 261664040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (327991680).

261664040 is an abundant number, since it is smaller than the sum of its proper divisors (394319320).

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

261664040 is a wasteful number, since it uses less digits than its factorization.

261664040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12722 (or 12718 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 261664040 is about 16176.0328881960. The cubic root of 261664040 is about 639.6091689305.

The spelling of 261664040 in words is "two hundred sixty-one million, six hundred sixty-four thousand, forty".