66820393 has 2 divisors, whose sum is σ = 66820394. Its totient is φ = 66820392.

The previous prime is 66820367. The next prime is 66820423. The reversal of 66820393 is 39302866.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66781584 + 38809 = 8172^2 + 197^2 .

It is a cyclic number.

It is not a de Polignac number, because 66820393 - 2⁵ = 66820361 is a prime.

It is not a weakly prime, because it can be changed into another prime (66820343) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33410196 + 33410197.

It is an arithmetic number, because the mean of its divisors is an integer number (33410197).

Almost surely, 2^66820393 is an apocalyptic number.

It is an amenable number.

66820393 is a deficient number, since it is larger than the sum of its proper divisors (1).

66820393 is an equidigital number, since it uses as much as digits as its factorization.

66820393 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 37.

The square root of 66820393 is about 8174.3741656472. The cubic root of 66820393 is about 405.7915586596.

The spelling of 66820393 in words is "sixty-six million, eight hundred twenty thousand, three hundred ninety-three".