139522021 has 2 divisors, whose sum is σ = 139522022. Its totient is φ = 139522020.

The previous prime is 139522013. The next prime is 139522039. The reversal of 139522021 is 120225931.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 116337796 + 23184225 = 10786^2 + 4815^2 .

It is a cyclic number.

It is not a de Polignac number, because 139522021 - 2³ = 139522013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139522001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69761010 + 69761011.

It is an arithmetic number, because the mean of its divisors is an integer number (69761011).

Almost surely, 2^139522021 is an apocalyptic number.

It is an amenable number.

139522021 is a deficient number, since it is larger than the sum of its proper divisors (1).

139522021 is an equidigital number, since it uses as much as digits as its factorization.

139522021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 139522021 is about 11811.9439974968. The cubic root of 139522021 is about 518.6578070837.

Adding to 139522021 its reverse (120225931), we get a palindrome (259747952).

The spelling of 139522021 in words is "one hundred thirty-nine million, five hundred twenty-two thousand, twenty-one".