66547031021 has 2 divisors, whose sum is σ = 66547031022. Its totient is φ = 66547031020.

The previous prime is 66547031011. The next prime is 66547031077. The reversal of 66547031021 is 12013074566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66321700900 + 225330121 = 257530^2 + 15011^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66547031021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66547031011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33273515510 + 33273515511.

It is an arithmetic number, because the mean of its divisors is an integer number (33273515511).

Almost surely, 2^66547031021 is an apocalyptic number.

It is an amenable number.

66547031021 is a deficient number, since it is larger than the sum of its proper divisors (1).

66547031021 is an equidigital number, since it uses as much as digits as its factorization.

66547031021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 35.

The spelling of 66547031021 in words is "sixty-six billion, five hundred forty-seven million, thirty-one thousand, twenty-one".