139236821 has 4 divisors (see below), whose sum is σ = 139754700. Its totient is φ = 138718944.

The previous prime is 139236793. The next prime is 139236829. The reversal of 139236821 is 128632931.

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 14668900 + 124567921 = 3830^2 + 11161^2 .

It is a cyclic number.

It is not a de Polignac number, because 139236821 - 2¹⁴ = 139220437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (139236829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 258536 + ... + 259073.

It is an arithmetic number, because the mean of its divisors is an integer number (34938675).

Almost surely, 2^139236821 is an apocalyptic number.

It is an amenable number.

139236821 is a deficient number, since it is larger than the sum of its proper divisors (517879).

139236821 is an equidigital number, since it uses as much as digits as its factorization.

139236821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 517878.

The product of its digits is 15552, while the sum is 35.

The square root of 139236821 is about 11799.8652958413. The cubic root of 139236821 is about 518.3041661081.

The spelling of 139236821 in words is "one hundred thirty-nine million, two hundred thirty-six thousand, eight hundred twenty-one".