261431216661345 has 32 divisors (see below), whose sum is σ = 423336830257152. Its totient is φ = 137747745193152.

The previous prime is 261431216661319. The next prime is 261431216661347. The reversal of 261431216661345 is 543166612134162.

It is not a de Polignac number, because 261431216661345 - 2¹² = 261431216657249 is a prime.

It is a super-2 number, since 2×261431216661345² (a number of 30 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261431216661347) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 72194374 + ... + 75729056.

It is an arithmetic number, because the mean of its divisors is an integer number (13229275945536).

Almost surely, 2^{261431216661345} is an apocalyptic number.

It is an amenable number.

261431216661345 is a deficient number, since it is larger than the sum of its proper divisors (161905613595807).

261431216661345 is a wasteful number, since it uses less digits than its factorization.

261431216661345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3594181.

The product of its digits is 3732480, while the sum is 51.

The spelling of 261431216661345 in words is "two hundred sixty-one trillion, four hundred thirty-one billion, two hundred sixteen million, six hundred sixty-one thousand, three hundred forty-five".