21973928 has 16 divisors (see below), whose sum is σ = 43624980. Its totient is φ = 10340608.

The previous prime is 21973907. The next prime is 21973933. The reversal of 21973928 is 82937912.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20811844 + 1162084 = 4562^2 + 1078^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80651 + ... + 80922.

Almost surely, 2^21973928 is an apocalyptic number.

It is an amenable number.

21973928 is a deficient number, since it is larger than the sum of its proper divisors (21651052).

21973928 is a wasteful number, since it uses less digits than its factorization.

21973928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161596 (or 161592 counting only the distinct ones).

The product of its digits is 54432, while the sum is 41.

The square root of 21973928 is about 4687.6356513705. The cubic root of 21973928 is about 280.0932002666.

It can be divided in two parts, 219 and 73928, that added together give a palindrome (74147).

The spelling of 21973928 in words is "twenty-one million, nine hundred seventy-three thousand, nine hundred twenty-eight".