66398819 has 2 divisors, whose sum is σ = 66398820. Its totient is φ = 66398818.

The previous prime is 66398747. The next prime is 66398851. The reversal of 66398819 is 91889366.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66398819 - 2¹² = 66394723 is a prime.

It is a super-2 number, since 2×66398819² = 8817606329189522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (66398219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33199409 + 33199410.

It is an arithmetic number, because the mean of its divisors is an integer number (33199410).

Almost surely, 2^66398819 is an apocalyptic number.

66398819 is a deficient number, since it is larger than the sum of its proper divisors (1).

66398819 is an equidigital number, since it uses as much as digits as its factorization.

66398819 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 559872, while the sum is 50.

The square root of 66398819 is about 8148.5470484007. The cubic root of 66398819 is about 404.9363696204.

The spelling of 66398819 in words is "sixty-six million, three hundred ninety-eight thousand, eight hundred nineteen".