21221145 has 48 divisors (see below), whose sum is σ = 41101632. Its totient is φ = 10039680.

The previous prime is 21221131. The next prime is 21221153. The reversal of 21221145 is 54112212.

It is not a de Polignac number, because 21221145 - 2⁴ = 21221129 is a prime.

It is a super-2 number, since 2×21221145² = 900673990222050, which contains 22 as substring.

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 47 ways as a sum of consecutive naturals, for example, 20787 + ... + 21783.

It is an arithmetic number, because the mean of its divisors is an integer number (856284).

Almost surely, 2^21221145 is an apocalyptic number.

It is an amenable number.

21221145 is a deficient number, since it is larger than the sum of its proper divisors (19880487).

21221145 is a wasteful number, since it uses less digits than its factorization.

21221145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1062 (or 1059 counting only the distinct ones).

The product of its digits is 160, while the sum is 18.

The square root of 21221145 is about 4606.6414012814. The cubic root of 21221145 is about 276.8574859791.

Adding to 21221145 its reverse (54112212), we get a palindrome (75333357).

The spelling of 21221145 in words is "twenty-one million, two hundred twenty-one thousand, one hundred forty-five".