261666401311245 has 48 divisors (see below), whose sum is σ = 487150173449280. Its totient is φ = 119586932833536.

The previous prime is 261666401311241. The next prime is 261666401311331. The reversal of 261666401311245 is 542113104666162.

It is not a de Polignac number, because 261666401311245 - 2² = 261666401311241 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 261666401311194 and 261666401311203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261666401311241) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 44859312 + ... + 50355641.

It is an arithmetic number, because the mean of its divisors is an integer number (10148961946860).

Almost surely, 2^{261666401311245} is an apocalyptic number.

It is an amenable number.

261666401311245 is a deficient number, since it is larger than the sum of its proper divisors (225483772138035).

261666401311245 is a wasteful number, since it uses less digits than its factorization.

261666401311245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95218714 (or 95218707 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 48.

The spelling of 261666401311245 in words is "two hundred sixty-one trillion, six hundred sixty-six billion, four hundred one million, three hundred eleven thousand, two hundred forty-five".