21644061 has 8 divisors (see below), whose sum is σ = 28884000. Its totient is φ = 14416752.

The previous prime is 21644053. The next prime is 21644089. The reversal of 21644061 is 16044612.

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

It is not a de Polignac number, because 21644061 - 2³ = 21644053 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21644011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2091 + ... + 6903.

It is an arithmetic number, because the mean of its divisors is an integer number (3610500).

Almost surely, 2^21644061 is an apocalyptic number.

It is an amenable number.

21644061 is a deficient number, since it is larger than the sum of its proper divisors (7239939).

21644061 is a wasteful number, since it uses less digits than its factorization.

21644061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6315.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21644061 is about 4652.3178094365. The cubic root of 21644061 is about 278.6845653349.

Adding to 21644061 its reverse (16044612), we get a palindrome (37688673).

The spelling of 21644061 in words is "twenty-one million, six hundred forty-four thousand, sixty-one".