66638587 has 2 divisors, whose sum is σ = 66638588. Its totient is φ = 66638586.

The previous prime is 66638573. The next prime is 66638609. The reversal of 66638587 is 78583666.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66638587 - 2¹⁹ = 66114299 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66638587.

It is not a weakly prime, because it can be changed into another prime (66638287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33319293 + 33319294.

It is an arithmetic number, because the mean of its divisors is an integer number (33319294).

Almost surely, 2^66638587 is an apocalyptic number.

66638587 is a deficient number, since it is larger than the sum of its proper divisors (1).

66638587 is an equidigital number, since it uses as much as digits as its factorization.

66638587 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1451520, while the sum is 49.

The square root of 66638587 is about 8163.2461067886. The cubic root of 66638587 is about 405.4231963088.

The spelling of 66638587 in words is "sixty-six million, six hundred thirty-eight thousand, five hundred eighty-seven".