21151984 has 20 divisors (see below), whose sum is σ = 46836784. Its totient is φ = 9065088.

The previous prime is 21151981. The next prime is 21152003. The reversal of 21151984 is 48915112.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21151981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 94317 + ... + 94540.

Almost surely, 2^21151984 is an apocalyptic number.

It is an amenable number.

21151984 is an abundant number, since it is smaller than the sum of its proper divisors (25684800).

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

21151984 is a wasteful number, since it uses less digits than its factorization.

21151984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188872 (or 188866 counting only the distinct ones).

The product of its digits is 2880, while the sum is 31.

The square root of 21151984 is about 4599.1286131179. The cubic root of 21151984 is about 276.5563935303.

The spelling of 21151984 in words is "twenty-one million, one hundred fifty-one thousand, nine hundred eighty-four".