138470921 has 4 divisors (see below), whose sum is σ = 138943812. Its totient is φ = 137998032.

The previous prime is 138470903. The next prime is 138470929. The reversal of 138470921 is 129074831.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 129709321 + 8761600 = 11389^2 + 2960^2 .

It is a cyclic number.

It is not a de Polignac number, because 138470921 - 2¹⁰ = 138469897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138470929) 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, 236006 + ... + 236591.

It is an arithmetic number, because the mean of its divisors is an integer number (34735953).

Almost surely, 2^138470921 is an apocalyptic number.

It is an amenable number.

138470921 is a deficient number, since it is larger than the sum of its proper divisors (472891).

138470921 is an equidigital number, since it uses as much as digits as its factorization.

138470921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 472890.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 138470921 is about 11767.3667827599. The cubic root of 138470921 is about 517.3520729766.

The spelling of 138470921 in words is "one hundred thirty-eight million, four hundred seventy thousand, nine hundred twenty-one".