139921 has 2 divisors, whose sum is σ = 139922. Its totient is φ = 139920.

The previous prime is 139907. The next prime is 139939. The reversal of 139921 is 129931.

139921 = 264² + 265².

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70225 + 69696 = 265^2 + 264^2 .

It is a cyclic number.

It is not a de Polignac number, because 139921 - 2⁹ = 139409 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69960 + 69961.

It is an arithmetic number, because the mean of its divisors is an integer number (69961).

2¹³⁹⁹²¹ is an apocalyptic number.

139921 is the 265-th centered square number.

It is an amenable number.

139921 is a deficient number, since it is larger than the sum of its proper divisors (1).

139921 is an equidigital number, since it uses as much as digits as its factorization.

139921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 486, while the sum is 25.

The square root of 139921 is about 374.0601555900. The cubic root of 139921 is about 51.9151723467.

The spelling of 139921 in words is "one hundred thirty-nine thousand, nine hundred twenty-one".