261440643576545 has 16 divisors (see below), whose sum is σ = 319064518765440. Its totient is φ = 205595757427200.

The previous prime is 261440643576451. The next prime is 261440643576547. The reversal of 261440643576545 is 545675346044162.

It is a happy number.

It is not a de Polignac number, because 261440643576545 - 2⁸ = 261440643576289 is a prime.

It is a super-2 number, since 2×261440643576545² (a number of 30 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261440643576547) 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, 20279216 + ... + 30563505.

It is an arithmetic number, because the mean of its divisors is an integer number (19941532422840).

Almost surely, 2^{261440643576545} is an apocalyptic number.

It is an amenable number.

261440643576545 is a deficient number, since it is larger than the sum of its proper divisors (57623875188895).

261440643576545 is a wasteful number, since it uses less digits than its factorization.

261440643576545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50860216.

The product of its (nonzero) digits is 290304000, while the sum is 62.

The spelling of 261440643576545 in words is "two hundred sixty-one trillion, four hundred forty billion, six hundred forty-three million, five hundred seventy-six thousand, five hundred forty-five".