138921533 has 6 divisors (see below), whose sum is σ = 141630174. Its totient is φ = 136216184.

The previous prime is 138921527. The next prime is 138921539. The reversal of 138921533 is 335129831.

It is a happy number.

138921533 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (138921527) and next prime (138921539).

It can be written as a sum of positive squares in only one way, i.e., 128436889 + 10484644 = 11333^2 + 3238^2 .

It is not a de Polignac number, because 138921533 - 2⁶ = 138921469 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 138921493 and 138921502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138921539) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 84998 + ... + 86616.

It is an arithmetic number, because the mean of its divisors is an integer number (23605029).

Almost surely, 2^138921533 is an apocalyptic number.

It is an amenable number.

138921533 is a deficient number, since it is larger than the sum of its proper divisors (2708641).

138921533 is an frugal number, since it uses more digits than its factorization.

138921533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3291 (or 1672 counting only the distinct ones).

The product of its digits is 19440, while the sum is 35.

The square root of 138921533 is about 11786.4979107452. The cubic root of 138921533 is about 517.9126542846.

It can be divided in two parts, 1389 and 21533, that added together give a palindrome (22922).

The spelling of 138921533 in words is "one hundred thirty-eight million, nine hundred twenty-one thousand, five hundred thirty-three".