261533533360721 has 16 divisors (see below), whose sum is σ = 280493573683200. Its totient is φ = 243131487148368.

The previous prime is 261533533360709. The next prime is 261533533360741. The reversal of 261533533360721 is 127063335335162.

It is a happy number.

261533533360721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 261533533360721 - 2¹⁴ = 261533533344337 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261533533360721.

It is not an unprimeable number, because it can be changed into a prime (261533533360741) 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, 534232421 + ... + 534721746.

It is an arithmetic number, because the mean of its divisors is an integer number (17530848355200).

Almost surely, 2^{261533533360721} is an apocalyptic number.

It is an amenable number.

261533533360721 is a deficient number, since it is larger than the sum of its proper divisors (18960040322479).

261533533360721 is a wasteful number, since it uses less digits than its factorization.

261533533360721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1068954428.

The product of its (nonzero) digits is 6123600, while the sum is 50.

Adding to 261533533360721 its reverse (127063335335162), we get a palindrome (388596868695883).

The spelling of 261533533360721 in words is "two hundred sixty-one trillion, five hundred thirty-three billion, five hundred thirty-three million, three hundred sixty thousand, seven hundred twenty-one".