261646250065601 has 4 divisors (see below), whose sum is σ = 263379006688704. Its totient is φ = 259913493442500.

The previous prime is 261646250065597. The next prime is 261646250065637. The reversal of 261646250065601 is 106560052646162.

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 261646250065601 - 2² = 261646250065597 is a prime.

It is a super-2 number, since 2×261646250065601² (a number of 30 digits) contains 22 as substring.

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 261646250065601.

It is not an unprimeable number, because it can be changed into a prime (261646250065691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 866378311325 + ... + 866378311626.

It is an arithmetic number, because the mean of its divisors is an integer number (65844751672176).

Almost surely, 2^{261646250065601} is an apocalyptic number.

It is an amenable number.

261646250065601 is a deficient number, since it is larger than the sum of its proper divisors (1732756623103).

261646250065601 is a wasteful number, since it uses less digits than its factorization.

261646250065601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1732756623102.

The product of its (nonzero) digits is 3110400, while the sum is 50.

The spelling of 261646250065601 in words is "two hundred sixty-one trillion, six hundred forty-six billion, two hundred fifty million, sixty-five thousand, six hundred one".