139906021 has 2 divisors, whose sum is σ = 139906022. Its totient is φ = 139906020.

The previous prime is 139906009. The next prime is 139906027. The reversal of 139906021 is 120609931.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 96530625 + 43375396 = 9825^2 + 6586^2 .

It is a cyclic number.

It is not a de Polignac number, because 139906021 - 2⁵ = 139905989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139906027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69953010 + 69953011.

It is an arithmetic number, because the mean of its divisors is an integer number (69953011).

Almost surely, 2^139906021 is an apocalyptic number.

It is an amenable number.

139906021 is a deficient number, since it is larger than the sum of its proper divisors (1).

139906021 is an equidigital number, since it uses as much as digits as its factorization.

139906021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 139906021 is about 11828.1875619217. The cubic root of 139906021 is about 519.1331971767.

The spelling of 139906021 in words is "one hundred thirty-nine million, nine hundred six thousand, twenty-one".