21221641 has 8 divisors (see below), whose sum is σ = 24845184. Its totient is φ = 17746080.

The previous prime is 21221633. The next prime is 21221653. The reversal of 21221641 is 14612212.

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

It is a cyclic number.

It is not a de Polignac number, because 21221641 - 2³ = 21221633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21221621) 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, 36685 + ... + 37258.

It is an arithmetic number, because the mean of its divisors is an integer number (3105648).

Almost surely, 2^21221641 is an apocalyptic number.

It is an amenable number.

21221641 is a deficient number, since it is larger than the sum of its proper divisors (3623543).

21221641 is an equidigital number, since it uses as much as digits as its factorization.

21221641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73991.

The product of its digits is 192, while the sum is 19.

The square root of 21221641 is about 4606.6952362838. The cubic root of 21221641 is about 276.8596429511.

Adding to 21221641 its reverse (14612212), we get a palindrome (35833853).

The spelling of 21221641 in words is "twenty-one million, two hundred twenty-one thousand, six hundred forty-one".