66977839 has 2 divisors, whose sum is σ = 66977840. Its totient is φ = 66977838.

The previous prime is 66977837. The next prime is 66977857. The reversal of 66977839 is 93877966.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66977839 - 2¹ = 66977837 is a prime.

Together with 66977837, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 66977839.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66977837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33488919 + 33488920.

It is an arithmetic number, because the mean of its divisors is an integer number (33488920).

Almost surely, 2^66977839 is an apocalyptic number.

66977839 is a deficient number, since it is larger than the sum of its proper divisors (1).

66977839 is an equidigital number, since it uses as much as digits as its factorization.

66977839 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3429216, while the sum is 55.

The square root of 66977839 is about 8183.9989613880. The cubic root of 66977839 is about 406.1100250232.

The spelling of 66977839 in words is "sixty-six million, nine hundred seventy-seven thousand, eight hundred thirty-nine".