21956378289 has 12 divisors (see below), whose sum is σ = 30603347376. Its totient is φ = 14001167752.

The previous prime is 21956378287. The next prime is 21956378293. The reversal of 21956378289 is 98287365912.

It is not a de Polignac number, because 21956378289 - 2¹ = 21956378287 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21956378287) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6915987 + ... + 6919160.

It is an arithmetic number, because the mean of its divisors is an integer number (2550278948).

Almost surely, 2^21956378289 is an apocalyptic number.

It is an amenable number.

21956378289 is a deficient number, since it is larger than the sum of its proper divisors (8646969087).

21956378289 is a wasteful number, since it uses less digits than its factorization.

21956378289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13835196 (or 13835173 counting only the distinct ones).

The product of its digits is 13063680, while the sum is 60.

The spelling of 21956378289 in words is "twenty-one billion, nine hundred fifty-six million, three hundred seventy-eight thousand, two hundred eighty-nine".