21978893392 has 10 divisors (see below), whose sum is σ = 42584105978. Its totient is φ = 10989446688.

The previous prime is 21978893389. The next prime is 21978893399. The reversal of 21978893392 is 29339887912.

It can be written as a sum of positive squares in only one way, i.e., 19500446736 + 2478446656 = 139644^2 + 49784^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21978893392.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21978893399) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 686840403 + ... + 686840434.

Almost surely, 2^21978893392 is an apocalyptic number.

It is an amenable number.

21978893392 is a deficient number, since it is larger than the sum of its proper divisors (20605212586).

21978893392 is a wasteful number, since it uses less digits than its factorization.

21978893392 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1373680845 (or 1373680839 counting only the distinct ones).

The product of its digits is 11757312, while the sum is 61.

The spelling of 21978893392 in words is "twenty-one billion, nine hundred seventy-eight million, eight hundred ninety-three thousand, three hundred ninety-two".