665961808961064 has 1152 divisors, whose sum is σ = 2231605748736000. Its totient is φ = 164803605120000.

The previous prime is 665961808961063. The next prime is 665961808961081. The reversal of 665961808961064 is 460169808169566.

It is a super-2 number, since 2×665961808961064² (a number of 30 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (665961808961063) by changing a digit.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 341694103162 + ... + 341694105110.

It is an arithmetic number, because the mean of its divisors is an integer number (1937157768000).

Almost surely, 2^{665961808961064} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665961808961064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1115802874368000).

665961808961064 is an abundant number, since it is smaller than the sum of its proper divisors (1565643939774936).

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

665961808961064 is a wasteful number, since it uses less digits than its factorization.

665961808961064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3187 (or 3165 counting only the distinct ones).

The product of its (nonzero) digits is 806215680, while the sum is 75.

The spelling of 665961808961064 in words is "six hundred sixty-five trillion, nine hundred sixty-one billion, eight hundred eight million, nine hundred sixty-one thousand, sixty-four".