21309044 has 12 divisors (see below), whose sum is σ = 37325568. Its totient is φ = 10644600.

The previous prime is 21309023. The next prime is 21309061. The reversal of 21309044 is 44090312.

It is a super-3 number, since 3×21309044³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

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, 4589 + ... + 7979.

It is an arithmetic number, because the mean of its divisors is an integer number (3110464).

Almost surely, 2^21309044 is an apocalyptic number.

It is an amenable number.

21309044 is a deficient number, since it is larger than the sum of its proper divisors (16016524).

21309044 is a wasteful number, since it uses less digits than its factorization.

21309044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4966 (or 4964 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21309044 is about 4616.1720071938. The cubic root of 21309044 is about 277.2392117479.

Adding to 21309044 its reverse (44090312), we get a palindrome (65399356).

The spelling of 21309044 in words is "twenty-one million, three hundred nine thousand, forty-four".