138021553 has 2 divisors, whose sum is σ = 138021554. Its totient is φ = 138021552.

The previous prime is 138021509. The next prime is 138021557. The reversal of 138021553 is 355120831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 132319009 + 5702544 = 11503^2 + 2388^2 .

It is a cyclic number.

It is not a de Polignac number, because 138021553 - 2⁹ = 138021041 is a prime.

It is not a weakly prime, because it can be changed into another prime (138021557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69010776 + 69010777.

It is an arithmetic number, because the mean of its divisors is an integer number (69010777).

Almost surely, 2^138021553 is an apocalyptic number.

It is an amenable number.

138021553 is a deficient number, since it is larger than the sum of its proper divisors (1).

138021553 is an equidigital number, since it uses as much as digits as its factorization.

138021553 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 138021553 is about 11748.2574452554. The cubic root of 138021553 is about 516.7918268176.

The spelling of 138021553 in words is "one hundred thirty-eight million, twenty-one thousand, five hundred fifty-three".