21155984 has 40 divisors (see below), whose sum is σ = 42393120. Its totient is φ = 10222848.

The previous prime is 21155977. The next prime is 21155999. The reversal of 21155984 is 48955112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68759 + ... + 69065.

It is an arithmetic number, because the mean of its divisors is an integer number (1059828).

Almost surely, 2^21155984 is an apocalyptic number.

It is an amenable number.

21155984 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

21155984 is a wasteful number, since it uses less digits than its factorization.

21155984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 447 (or 441 counting only the distinct ones).

The product of its digits is 14400, while the sum is 35.

The square root of 21155984 is about 4599.5634575468. The cubic root of 21155984 is about 276.5738253994.

The spelling of 21155984 in words is "twenty-one million, one hundred fifty-five thousand, nine hundred eighty-four".