261684001109 has 4 divisors (see below), whose sum is σ = 261686008320. Its totient is φ = 261681993900.

The previous prime is 261684001087. The next prime is 261684001193. The reversal of 261684001109 is 901100486162.

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, and also an emirpimes, since its reverse is a distinct semiprime: 901100486162 = 2 ⋅450550243081.

It is a cyclic number.

It is not a de Polignac number, because 261684001109 - 2¹² = 261683997013 is a prime.

It is a super-2 number, since 2×261684001109² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261684001409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 793367 + ... + 1073684.

It is an arithmetic number, because the mean of its divisors is an integer number (65421502080).

Almost surely, 2^261684001109 is an apocalyptic number.

It is an amenable number.

261684001109 is a deficient number, since it is larger than the sum of its proper divisors (2007211).

261684001109 is a wasteful number, since it uses less digits than its factorization.

261684001109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2007210.

The product of its (nonzero) digits is 20736, while the sum is 38.

The spelling of 261684001109 in words is "two hundred sixty-one billion, six hundred eighty-four million, one thousand, one hundred nine".