261330721 has 8 divisors (see below), whose sum is σ = 263761344. Its totient is φ = 258906960.

The previous prime is 261330709. The next prime is 261330743. The reversal of 261330721 is 127033162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 261330721 - 2¹⁹ = 260806433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261330781) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 103156 + ... + 105658.

It is an arithmetic number, because the mean of its divisors is an integer number (32970168).

Almost surely, 2^261330721 is an apocalyptic number.

It is an amenable number.

261330721 is a deficient number, since it is larger than the sum of its proper divisors (2430623).

261330721 is a wasteful number, since it uses less digits than its factorization.

261330721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3431.

The product of its (nonzero) digits is 1512, while the sum is 25.

The square root of 261330721 is about 16165.7267389994. The cubic root of 261330721 is about 639.3374662312.

Adding to 261330721 its reverse (127033162), we get a palindrome (388363883).

The spelling of 261330721 in words is "two hundred sixty-one million, three hundred thirty thousand, seven hundred twenty-one".