66439799 has 2 divisors, whose sum is σ = 66439800. Its totient is φ = 66439798.

The previous prime is 66439777. The next prime is 66439817. The reversal of 66439799 is 99793466.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66439799 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66439799.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66439759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33219899 + 33219900.

It is an arithmetic number, because the mean of its divisors is an integer number (33219900).

Almost surely, 2^66439799 is an apocalyptic number.

66439799 is a deficient number, since it is larger than the sum of its proper divisors (1).

66439799 is an equidigital number, since it uses as much as digits as its factorization.

66439799 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2204496, while the sum is 53.

The square root of 66439799 is about 8151.0612192524. The cubic root of 66439799 is about 405.0196586505.

The spelling of 66439799 in words is "sixty-six million, four hundred thirty-nine thousand, seven hundred ninety-nine".