39978139 has 2 divisors, whose sum is σ = 39978140. Its totient is φ = 39978138.

The previous prime is 39978137. The next prime is 39978143. The reversal of 39978139 is 93187993.

It is a weak prime.

It is an emirp because it is prime and its reverse (93187993) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 39978139 - 2¹ = 39978137 is a prime.

Together with 39978137, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 39978092 and 39978101.

It is not a weakly prime, because it can be changed into another prime (39978131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19989069 + 19989070.

It is an arithmetic number, because the mean of its divisors is an integer number (19989070).

Almost surely, 2^39978139 is an apocalyptic number.

39978139 is a deficient number, since it is larger than the sum of its proper divisors (1).

39978139 is an equidigital number, since it uses as much as digits as its factorization.

39978139 is an evil number, because the sum of its binary digits is even.

The product of its digits is 367416, while the sum is 49.

The square root of 39978139 is about 6322.8268203391. The cubic root of 39978139 is about 341.9328750082.

The spelling of 39978139 in words is "thirty-nine million, nine hundred seventy-eight thousand, one hundred thirty-nine".