21337644 has 12 divisors (see below), whose sum is σ = 49787864. Its totient is φ = 7112544.

The previous prime is 21337643. The next prime is 21337717. The reversal of 21337644 is 44673312.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (21337643) 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 3 ways as a sum of consecutive naturals, for example, 889057 + ... + 889080.

Almost surely, 2^21337644 is an apocalyptic number.

It is an amenable number.

21337644 is an abundant number, since it is smaller than the sum of its proper divisors (28450220).

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

21337644 is a wasteful number, since it uses less digits than its factorization.

21337644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1778144 (or 1778142 counting only the distinct ones).

The product of its digits is 12096, while the sum is 30.

The square root of 21337644 is about 4619.2687733017. The cubic root of 21337644 is about 277.3631887905.

The spelling of 21337644 in words is "twenty-one million, three hundred thirty-seven thousand, six hundred forty-four".