261666443207064 has 256 divisors, whose sum is σ = 800628397148160. Its totient is φ = 69638164992000.

The previous prime is 261666443207053. The next prime is 261666443207101. The reversal of 261666443207064 is 460702344666162.

It is a junction number, because it is equal to n+sod(n) for n = 261666443206995 and 261666443207013.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 84180874 + ... + 87233894.

It is an arithmetic number, because the mean of its divisors is an integer number (3127454676360).

Almost surely, 2^{261666443207064} is an apocalyptic number.

261666443207064 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261666443207064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (400314198574080).

261666443207064 is an abundant number, since it is smaller than the sum of its proper divisors (538961953941096).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261666443207064 is a wasteful number, since it uses less digits than its factorization.

261666443207064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3053642 (or 3053638 counting only the distinct ones).

The product of its (nonzero) digits is 41803776, while the sum is 57.

The spelling of 261666443207064 in words is "two hundred sixty-one trillion, six hundred sixty-six billion, four hundred forty-three million, two hundred seven thousand, sixty-four".