21221138 has 16 divisors (see below), whose sum is σ = 33936000. Its totient is φ = 9923472.

The previous prime is 21221131. The next prime is 21221153. The reversal of 21221138 is 83112212.

It is not an unprimeable number, because it can be changed into a prime (21221131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 533 + ... + 6536.

It is an arithmetic number, because the mean of its divisors is an integer number (2121000).

Almost surely, 2^21221138 is an apocalyptic number.

21221138 is a deficient number, since it is larger than the sum of its proper divisors (12714862).

21221138 is a wasteful number, since it uses less digits than its factorization.

21221138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7169.

The product of its digits is 192, while the sum is 20.

The square root of 21221138 is about 4606.6406415087. The cubic root of 21221138 is about 276.8574555378.

The spelling of 21221138 in words is "twenty-one million, two hundred twenty-one thousand, one hundred thirty-eight".