21431178439 has 4 divisors (see below), whose sum is σ = 23379467400. Its totient is φ = 19482889480.

The previous prime is 21431178407. The next prime is 21431178463. The reversal of 21431178439 is 93487113412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21431178439 - 2⁵ = 21431178407 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21431178395 and 21431178404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431176439) 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, 974144464 + ... + 974144485.

It is an arithmetic number, because the mean of its divisors is an integer number (5844866850).

Almost surely, 2^21431178439 is an apocalyptic number.

21431178439 is a deficient number, since it is larger than the sum of its proper divisors (1948288961).

21431178439 is a wasteful number, since it uses less digits than its factorization.

21431178439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1948288960.

The product of its digits is 145152, while the sum is 43.

The spelling of 21431178439 in words is "twenty-one billion, four hundred thirty-one million, one hundred seventy-eight thousand, four hundred thirty-nine".