21879331421 has 4 divisors (see below), whose sum is σ = 23030875200. Its totient is φ = 20727787644.

The previous prime is 21879331391. The next prime is 21879331447. The reversal of 21879331421 is 12413397812.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21879331421 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 (21879331921) 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, 575771861 + ... + 575771898.

It is an arithmetic number, because the mean of its divisors is an integer number (5757718800).

Almost surely, 2^21879331421 is an apocalyptic number.

It is an amenable number.

21879331421 is a deficient number, since it is larger than the sum of its proper divisors (1151543779).

21879331421 is a wasteful number, since it uses less digits than its factorization.

21879331421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1151543778.

The product of its digits is 72576, while the sum is 41.

The spelling of 21879331421 in words is "twenty-one billion, eight hundred seventy-nine million, three hundred thirty-one thousand, four hundred twenty-one".