21221140 has 12 divisors (see below), whose sum is σ = 44564436. Its totient is φ = 8488448.

The previous prime is 21221131. The next prime is 21221153. The reversal of 21221140 is 4112212.

It is a happy number.

21221140 is nontrivially palindromic in base 9.

It can be written as a sum of positive squares in 2 ways, for example, as 9511056 + 11710084 = 3084^2 + 3422^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21221140.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 530509 + ... + 530548.

It is an arithmetic number, because the mean of its divisors is an integer number (3713703).

Almost surely, 2^21221140 is an apocalyptic number.

21221140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21221140 is an abundant number, since it is smaller than the sum of its proper divisors (23343296).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21221140 is a wasteful number, since it uses less digits than its factorization.

21221140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1061066 (or 1061064 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 21221140 is about 4606.6408585867. The cubic root of 21221140 is about 276.8574642353.

Adding to 21221140 its reverse (4112212), we get a palindrome (25333352).

The spelling of 21221140 in words is "twenty-one million, two hundred twenty-one thousand, one hundred forty".