66521640633 has 16 divisors (see below), whose sum is σ = 104861700480. Its totient is φ = 36701594496.

The previous prime is 66521640617. The next prime is 66521640637. The reversal of 66521640633 is 33604612566.

It is a happy number.

It is not a de Polignac number, because 66521640633 - 2⁴ = 66521640617 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66521640637) 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, 54614860 + ... + 54616077.

It is an arithmetic number, because the mean of its divisors is an integer number (6553856280).

Almost surely, 2^66521640633 is an apocalyptic number.

It is an amenable number.

66521640633 is a deficient number, since it is larger than the sum of its proper divisors (38340059847).

66521640633 is a wasteful number, since it uses less digits than its factorization.

66521640633 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109230976.

The product of its (nonzero) digits is 466560, while the sum is 42.

The spelling of 66521640633 in words is "sixty-six billion, five hundred twenty-one million, six hundred forty thousand, six hundred thirty-three".