138328921 has 4 divisors (see below), whose sum is σ = 140080000. Its totient is φ = 136577844.

The previous prime is 138328919. The next prime is 138328933. The reversal of 138328921 is 129823831.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 138328921 - 2¹ = 138328919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138328901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 875421 + ... + 875578.

It is an arithmetic number, because the mean of its divisors is an integer number (35020000).

Almost surely, 2^138328921 is an apocalyptic number.

It is an amenable number.

138328921 is a deficient number, since it is larger than the sum of its proper divisors (1751079).

138328921 is an equidigital number, since it uses as much as digits as its factorization.

138328921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1751078.

The product of its digits is 20736, while the sum is 37.

The square root of 138328921 is about 11761.3315997807. The cubic root of 138328921 is about 517.1751667106.

The spelling of 138328921 in words is "one hundred thirty-eight million, three hundred twenty-eight thousand, nine hundred twenty-one".