261721824 has 96 divisors (see below), whose sum is σ = 845591040. Its totient is φ = 69023232.

The previous prime is 261721813. The next prime is 261721829. The reversal of 261721824 is 428127162.

261721824 is digitally balanced in base 3, 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 (96).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261721829) 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, 6244 + ... + 23715.

It is an arithmetic number, because the mean of its divisors is an integer number (8808240).

Almost surely, 2^261721824 is an apocalyptic number.

261721824 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

261721824 is an abundant number, since it is smaller than the sum of its proper divisors (583869216).

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

261721824 is a wasteful number, since it uses less digits than its factorization.

261721824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29992 (or 29984 counting only the distinct ones).

The product of its digits is 10752, while the sum is 33.

The square root of 261721824 is about 16177.8188888367. The cubic root of 261721824 is about 639.6562476909.

Adding to 261721824 its reverse (428127162), we get a palindrome (689848986).

The spelling of 261721824 in words is "two hundred sixty-one million, seven hundred twenty-one thousand, eight hundred twenty-four".