21162644 has 6 divisors (see below), whose sum is σ = 37034634. Its totient is φ = 10581320.

The previous prime is 21162641. The next prime is 21162653. The reversal of 21162644 is 44626112.

It can be written as a sum of positive squares in only one way, i.e., 11303044 + 9859600 = 3362^2 + 3140^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21162641) 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 as a sum of consecutive naturals, namely, 2645327 + ... + 2645334.

It is an arithmetic number, because the mean of its divisors is an integer number (6172439).

Almost surely, 2^21162644 is an apocalyptic number.

It is an amenable number.

21162644 is a deficient number, since it is larger than the sum of its proper divisors (15871990).

21162644 is a wasteful number, since it uses less digits than its factorization.

21162644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5290665 (or 5290663 counting only the distinct ones).

The product of its digits is 2304, while the sum is 26.

The square root of 21162644 is about 4600.2873823273. The cubic root of 21162644 is about 276.6028445872.

Adding to 21162644 its reverse (44626112), we get a palindrome (65788756).

The spelling of 21162644 in words is "twenty-one million, one hundred sixty-two thousand, six hundred forty-four".