138847821 has 12 divisors (see below), whose sum is σ = 215356032. Its totient is φ = 79341528.

The previous prime is 138847783. The next prime is 138847843. The reversal of 138847821 is 128748831.

It is not a de Polignac number, because 138847821 - 2⁷ = 138847693 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138847871) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 472125 + ... + 472418.

It is an arithmetic number, because the mean of its divisors is an integer number (17946336).

Almost surely, 2^138847821 is an apocalyptic number.

It is an amenable number.

138847821 is a deficient number, since it is larger than the sum of its proper divisors (76508211).

138847821 is an equidigital number, since it uses as much as digits as its factorization.

138847821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 944560 (or 944553 counting only the distinct ones).

The product of its digits is 86016, while the sum is 42.

The square root of 138847821 is about 11783.3705279941. The cubic root of 138847821 is about 517.8210363021.

The spelling of 138847821 in words is "one hundred thirty-eight million, eight hundred forty-seven thousand, eight hundred twenty-one".