66438896389 has 2 divisors, whose sum is σ = 66438896390. Its totient is φ = 66438896388.

The previous prime is 66438896281. The next prime is 66438896393. The reversal of 66438896389 is 98369883466.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 33862256289 + 32576640100 = 184017^2 + 180490^2 .

It is a cyclic number.

It is not a de Polignac number, because 66438896389 - 2¹⁷ = 66438765317 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66438896089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33219448194 + 33219448195.

It is an arithmetic number, because the mean of its divisors is an integer number (33219448195).

Almost surely, 2^66438896389 is an apocalyptic number.

It is an amenable number.

66438896389 is a deficient number, since it is larger than the sum of its proper divisors (1).

66438896389 is an equidigital number, since it uses as much as digits as its factorization.

66438896389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 322486272, while the sum is 70.

The spelling of 66438896389 in words is "sixty-six billion, four hundred thirty-eight million, eight hundred ninety-six thousand, three hundred eighty-nine".