138877856688421 has 4 divisors (see below), whose sum is σ = 138882268201644. Its totient is φ = 138873445175200.

The previous prime is 138877856688407. The next prime is 138877856688449. The reversal of 138877856688421 is 124886658778831.

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 6859365283521 + 132018491404900 = 2619039^2 + 11489930^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138877856688421 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 (138877856688121) 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, 2205709390 + ... + 2205772351.

It is an arithmetic number, because the mean of its divisors is an integer number (34720567050411).

Almost surely, 2^{138877856688421} is an apocalyptic number.

It is an amenable number.

138877856688421 is a deficient number, since it is larger than the sum of its proper divisors (4411513223).

138877856688421 is an equidigital number, since it uses as much as digits as its factorization.

138877856688421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4411513222.

The product of its digits is 6936330240, while the sum is 82.

The spelling of 138877856688421 in words is "one hundred thirty-eight trillion, eight hundred seventy-seven billion, eight hundred fifty-six million, six hundred eighty-eight thousand, four hundred twenty-one".