66431534640 has 80 divisors (see below), whose sum is σ = 216776601600. Its totient is φ = 16782702336.

The previous prime is 66431534573. The next prime is 66431534641. The reversal of 66431534640 is 4643513466.

66431534640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 66431534592 and 66431534601.

It is not an unprimeable number, because it can be changed into a prime (66431534641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7279600 + ... + 7288719.

It is an arithmetic number, because the mean of its divisors is an integer number (2709707520).

Almost surely, 2^66431534640 is an apocalyptic number.

66431534640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66431534640 is an abundant number, since it is smaller than the sum of its proper divisors (150345066960).

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

66431534640 is a wasteful number, since it uses less digits than its factorization.

66431534640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14568354 (or 14568348 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 42.

The spelling of 66431534640 in words is "sixty-six billion, four hundred thirty-one million, five hundred thirty-four thousand, six hundred forty".