261958721 has 4 divisors (see below), whose sum is σ = 262801344. Its totient is φ = 261116100.

The previous prime is 261958703. The next prime is 261958733. The reversal of 261958721 is 127859162.

261958721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 261958721 - 2¹⁰ = 261957697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261958621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 420845 + ... + 421466.

It is an arithmetic number, because the mean of its divisors is an integer number (65700336).

Almost surely, 2^261958721 is an apocalyptic number.

It is an amenable number.

261958721 is a deficient number, since it is larger than the sum of its proper divisors (842623).

261958721 is an equidigital number, since it uses as much as digits as its factorization.

261958721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 842622.

The product of its digits is 60480, while the sum is 41.

The square root of 261958721 is about 16185.1388934417. The cubic root of 261958721 is about 639.8491840268.

The spelling of 261958721 in words is "two hundred sixty-one million, nine hundred fifty-eight thousand, seven hundred twenty-one".