66921639799040 has 72 divisors (see below), whose sum is σ = 172628874245688. Its totient is φ = 24709528535040.

The previous prime is 66921639799033. The next prime is 66921639799043. The reversal of 66921639799040 is 4099793612966.

It can be written as a sum of positive squares in 4 ways, for example, as 1337038940416 + 65584600858624 = 1156304^2 + 8098432^2 .

It is not an unprimeable number, because it can be changed into a prime (66921639799043) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2010849941 + ... + 2010883220.

Almost surely, 2^{66921639799040} is an apocalyptic number.

It is an amenable number.

66921639799040 is an abundant number, since it is smaller than the sum of its proper divisors (105707234446648).

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

66921639799040 is a wasteful number, since it uses less digits than its factorization.

66921639799040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4021733195 (or 4021733181 counting only the distinct ones).

The product of its (nonzero) digits is 238085568, while the sum is 71.

The spelling of 66921639799040 in words is "sixty-six trillion, nine hundred twenty-one billion, six hundred thirty-nine million, seven hundred ninety-nine thousand, forty".