139023821 has 2 divisors, whose sum is σ = 139023822. Its totient is φ = 139023820.

The previous prime is 139023811. The next prime is 139023847. The reversal of 139023821 is 128320931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 83521321 + 55502500 = 9139^2 + 7450^2 .

It is an emirp because it is prime and its reverse (128320931) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 139023821 - 2⁶ = 139023757 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139023811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69511910 + 69511911.

It is an arithmetic number, because the mean of its divisors is an integer number (69511911).

Almost surely, 2^139023821 is an apocalyptic number.

It is an amenable number.

139023821 is a deficient number, since it is larger than the sum of its proper divisors (1).

139023821 is an equidigital number, since it uses as much as digits as its factorization.

139023821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 139023821 is about 11790.8363146980. The cubic root of 139023821 is about 518.0397362222.

The spelling of 139023821 in words is "one hundred thirty-nine million, twenty-three thousand, eight hundred twenty-one".