21731278329 has 24 divisors (see below), whose sum is σ = 33051287360. Its totient is φ = 13721039712.

The previous prime is 21731278319. The next prime is 21731278357. The reversal of 21731278329 is 92387213712.

21731278329 is a `hidden beast` number, since 2 + 1 + 7 + 312 + 7 + 8 + 329 = 666.

It is not a de Polignac number, because 21731278329 - 2¹³ = 21731270137 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21731278319) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 642372 + ... + 675354.

Almost surely, 2^21731278329 is an apocalyptic number.

It is an amenable number.

21731278329 is a deficient number, since it is larger than the sum of its proper divisors (11320009031).

21731278329 is a wasteful number, since it uses less digits than its factorization.

21731278329 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36861 (or 36858 counting only the distinct ones).

The product of its digits is 254016, while the sum is 45.

The spelling of 21731278329 in words is "twenty-one billion, seven hundred thirty-one million, two hundred seventy-eight thousand, three hundred twenty-nine".