138861021 has 8 divisors (see below), whose sum is σ = 199390240. Its totient is φ = 85452912.

The previous prime is 138861013. The next prime is 138861053. The reversal of 138861021 is 120168831.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 138861021 - 2³ = 138861013 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 138861021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138861091) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1780231 + ... + 1780308.

It is an arithmetic number, because the mean of its divisors is an integer number (24923780).

Almost surely, 2^138861021 is an apocalyptic number.

It is an amenable number.

138861021 is a deficient number, since it is larger than the sum of its proper divisors (60529219).

138861021 is a wasteful number, since it uses less digits than its factorization.

138861021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3560555.

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 138861021 is about 11783.9306260687. The cubic root of 138861021 is about 517.8374452047.

The spelling of 138861021 in words is "one hundred thirty-eight million, eight hundred sixty-one thousand, twenty-one".