66138239 has 2 divisors, whose sum is σ = 66138240. Its totient is φ = 66138238.

The previous prime is 66138229. The next prime is 66138251. The reversal of 66138239 is 93283166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66138239 - 2¹⁶ = 66072703 is a prime.

It is a super-2 number, since 2×66138239² = 8748533316042242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66138209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33069119 + 33069120.

It is an arithmetic number, because the mean of its divisors is an integer number (33069120).

Almost surely, 2^66138239 is an apocalyptic number.

66138239 is a deficient number, since it is larger than the sum of its proper divisors (1).

66138239 is an equidigital number, since it uses as much as digits as its factorization.

66138239 is an evil number, because the sum of its binary digits is even.

The product of its digits is 46656, while the sum is 38.

The square root of 66138239 is about 8132.5419765286. The cubic root of 66138239 is about 404.4059552901.

The spelling of 66138239 in words is "sixty-six million, one hundred thirty-eight thousand, two hundred thirty-nine".