21288044 has 12 divisors (see below), whose sum is σ = 37810584. Its totient is φ = 10485024.

The previous prime is 21288031. The next prime is 21288049. The reversal of 21288044 is 44088212.

21288044 = T₂₅₇ + T₂₅₈ + ... + T₅₂₄.

It is a junction number, because it is equal to n+sod(n) for n = 21287998 and 21288016.

It is not an unprimeable number, because it can be changed into a prime (21288049) 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, 39449 + ... + 39984.

It is an arithmetic number, because the mean of its divisors is an integer number (3150882).

Almost surely, 2^21288044 is an apocalyptic number.

It is an amenable number.

21288044 is a deficient number, since it is larger than the sum of its proper divisors (16522540).

21288044 is a wasteful number, since it uses less digits than its factorization.

21288044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79504 (or 79502 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 29.

The square root of 21288044 is about 4613.8968345640. The cubic root of 21288044 is about 277.1481090057.

The spelling of 21288044 in words is "twenty-one million, two hundred eighty-eight thousand, forty-four".