138503221 has 2 divisors, whose sum is σ = 138503222. Its totient is φ = 138503220.

The previous prime is 138503213. The next prime is 138503243. The reversal of 138503221 is 122305831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 85359121 + 53144100 = 9239^2 + 7290^2 .

It is a cyclic number.

It is not a de Polignac number, because 138503221 - 2³ = 138503213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138503251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69251610 + 69251611.

It is an arithmetic number, because the mean of its divisors is an integer number (69251611).

Almost surely, 2^138503221 is an apocalyptic number.

It is an amenable number.

138503221 is a deficient number, since it is larger than the sum of its proper divisors (1).

138503221 is an equidigital number, since it uses as much as digits as its factorization.

138503221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 138503221 is about 11768.7391423211. The cubic root of 138503221 is about 517.3922960374.

It can be divided in two parts, 13850 and 3221, that added together give a palindrome (17071).

The spelling of 138503221 in words is "one hundred thirty-eight million, five hundred three thousand, two hundred twenty-one".