21224121 has 8 divisors (see below), whose sum is σ = 29788320. Its totient is φ = 13404672.

The previous prime is 21224087. The next prime is 21224123. The reversal of 21224121 is 12142212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-21224121 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21224121.

It is not an unprimeable number, because it can be changed into a prime (21224123) 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, 186120 + ... + 186233.

It is an arithmetic number, because the mean of its divisors is an integer number (3723540).

Almost surely, 2^21224121 is an apocalyptic number.

It is an amenable number.

21224121 is a deficient number, since it is larger than the sum of its proper divisors (8564199).

21224121 is a wasteful number, since it uses less digits than its factorization.

21224121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372375.

The product of its digits is 64, while the sum is 15.

The square root of 21224121 is about 4606.9644018594. The cubic root of 21224121 is about 276.8704273067.

Adding to 21224121 its reverse (12142212), we get a palindrome (33366333).

The spelling of 21224121 in words is "twenty-one million, two hundred twenty-four thousand, one hundred twenty-one".