66400005660 has 96 divisors (see below), whose sum is σ = 196787136000. Its totient is φ = 16682008320.

The previous prime is 66400005613. The next prime is 66400005671. The reversal of 66400005660 is 6650000466.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45441 + ... + 367239.

It is an arithmetic number, because the mean of its divisors is an integer number (2049866000).

Almost surely, 2^66400005660 is an apocalyptic number.

66400005660 is a gapful number since it is divisible by the number (60) 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 66400005660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (98393568000).

66400005660 is an abundant number, since it is smaller than the sum of its proper divisors (130387130340).

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

66400005660 is a wasteful number, since it uses less digits than its factorization.

66400005660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322011 (or 322009 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 33.

The spelling of 66400005660 in words is "sixty-six billion, four hundred million, five thousand, six hundred sixty".