21421779839 has 16 divisors (see below), whose sum is σ = 22085167104. Its totient is φ = 20770764000.

The previous prime is 21421779829. The next prime is 21421779887. The reversal of 21421779839 is 93897712412.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21421779839 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 (21421779829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1305989 + ... + 1322289.

It is an arithmetic number, because the mean of its divisors is an integer number (1380322944).

Almost surely, 2^21421779839 is an apocalyptic number.

21421779839 is a deficient number, since it is larger than the sum of its proper divisors (663387265).

21421779839 is a wasteful number, since it uses less digits than its factorization.

21421779839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16678.

The product of its digits is 1524096, while the sum is 53.

The spelling of 21421779839 in words is "twenty-one billion, four hundred twenty-one million, seven hundred seventy-nine thousand, eight hundred thirty-nine".