66888888889021 has 2 divisors, whose sum is σ = 66888888889022. Its totient is φ = 66888888889020.

The previous prime is 66888888888881. The next prime is 66888888889049. The reversal of 66888888889021 is 12098888888866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49920371739225 + 16968517149796 = 7065435^2 + 4119286^2 .

It is a cyclic number.

It is not a de Polignac number, because 66888888889021 - 2¹⁵ = 66888888856253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66888888589021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33444444444510 + 33444444444511.

It is an arithmetic number, because the mean of its divisors is an integer number (33444444444511).

Almost surely, 2^{66888888889021} is an apocalyptic number.

It is an amenable number.

66888888889021 is a deficient number, since it is larger than the sum of its proper divisors (1).

66888888889021 is an equidigital number, since it uses as much as digits as its factorization.

66888888889021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10871635968, while the sum is 88.

The spelling of 66888888889021 in words is "sixty-six trillion, eight hundred eighty-eight billion, eight hundred eighty-eight million, eight hundred eighty-nine thousand, twenty-one".