66138811 has 2 divisors, whose sum is σ = 66138812. Its totient is φ = 66138810.

The previous prime is 66138769. The next prime is 66138817. The reversal of 66138811 is 11883166.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66138811 is a prime.

It is not a weakly prime, because it can be changed into another prime (66138817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33069405 + 33069406.

It is an arithmetic number, because the mean of its divisors is an integer number (33069406).

Almost surely, 2^66138811 is an apocalyptic number.

66138811 is a deficient number, since it is larger than the sum of its proper divisors (1).

66138811 is an equidigital number, since it uses as much as digits as its factorization.

66138811 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6912, while the sum is 34.

The square root of 66138811 is about 8132.5771438087. The cubic root of 66138811 is about 404.4071211287.

The spelling of 66138811 in words is "sixty-six million, one hundred thirty-eight thousand, eight hundred eleven".