138466921 has 4 divisors (see below), whose sum is σ = 146612052. Its totient is φ = 130321792.

The previous prime is 138466919. The next prime is 138466931. The reversal of 138466921 is 129664831.

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 91393600 + 47073321 = 9560^2 + 6861^2 .

It is a cyclic number.

It is not a de Polignac number, because 138466921 - 2¹ = 138466919 is a prime.

It is a super-2 number, since 2×138466921² = 38346176422440482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138466931) 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 in 3 ways as a sum of consecutive naturals, for example, 4072540 + ... + 4072573.

It is an arithmetic number, because the mean of its divisors is an integer number (36653013).

Almost surely, 2^138466921 is an apocalyptic number.

It is an amenable number.

138466921 is a deficient number, since it is larger than the sum of its proper divisors (8145131).

138466921 is an equidigital number, since it uses as much as digits as its factorization.

138466921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8145130.

The product of its digits is 62208, while the sum is 40.

The square root of 138466921 is about 11767.1968199737. The cubic root of 138466921 is about 517.3470913574.

The spelling of 138466921 in words is "one hundred thirty-eight million, four hundred sixty-six thousand, nine hundred twenty-one".