21678044 has 6 divisors (see below), whose sum is σ = 37936584. Its totient is φ = 10839020.

The previous prime is 21678037. The next prime is 21678049. The reversal of 21678044 is 44087612.

It is a self number, because there is not a number n which added to its sum of digits gives 21678044.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2709752 + ... + 2709759.

It is an arithmetic number, because the mean of its divisors is an integer number (6322764).

Almost surely, 2^21678044 is an apocalyptic number.

It is an amenable number.

21678044 is a deficient number, since it is larger than the sum of its proper divisors (16258540).

21678044 is a wasteful number, since it uses less digits than its factorization.

21678044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5419515 (or 5419513 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 32.

The square root of 21678044 is about 4655.9686425061. The cubic root of 21678044 is about 278.8303418197.

The spelling of 21678044 in words is "twenty-one million, six hundred seventy-eight thousand, forty-four".