66779987 has 2 divisors, whose sum is σ = 66779988. Its totient is φ = 66779986.

The previous prime is 66779981. The next prime is 66780031. The reversal of 66779987 is 78997766.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66779987 - 2¹⁶ = 66714451 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66779981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33389993 + 33389994.

It is an arithmetic number, because the mean of its divisors is an integer number (33389994).

Almost surely, 2^66779987 is an apocalyptic number.

66779987 is a deficient number, since it is larger than the sum of its proper divisors (1).

66779987 is an equidigital number, since it uses as much as digits as its factorization.

66779987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8001504, while the sum is 59.

The square root of 66779987 is about 8171.9022877173. The cubic root of 66779987 is about 405.7097487059.

The spelling of 66779987 in words is "sixty-six million, seven hundred seventy-nine thousand, nine hundred eighty-seven".