21379137849 has 6 divisors (see below), whose sum is σ = 30880976906. Its totient is φ = 14252758560.

The previous prime is 21379137847. The next prime is 21379137883. The reversal of 21379137849 is 94873197312.

It can be written as a sum of positive squares in only one way, i.e., 13872128400 + 7507009449 = 117780^2 + 86643^2 .

It is not a de Polignac number, because 21379137849 - 2¹ = 21379137847 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21379137795 and 21379137804.

It is not an unprimeable number, because it can be changed into a prime (21379137847) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1187729872 + ... + 1187729889.

Almost surely, 2^21379137849 is an apocalyptic number.

It is an amenable number.

21379137849 is a deficient number, since it is larger than the sum of its proper divisors (9501839057).

21379137849 is a wasteful number, since it uses less digits than its factorization.

21379137849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2375459767 (or 2375459764 counting only the distinct ones).

The product of its digits is 2286144, while the sum is 54.

The spelling of 21379137849 in words is "twenty-one billion, three hundred seventy-nine million, one hundred thirty-seven thousand, eight hundred forty-nine".