21051984 has 40 divisors (see below), whose sum is σ = 57585600. Its totient is φ = 6604288.

The previous prime is 21051977. The next prime is 21051991. The reversal of 21051984 is 48915012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21051977) and next prime (21051991).

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, 12084 + ... + 13715.

It is an arithmetic number, because the mean of its divisors is an integer number (1439640).

Almost surely, 2^21051984 is an apocalyptic number.

21051984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21051984 is an abundant number, since it is smaller than the sum of its proper divisors (36533616).

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

21051984 is a wasteful number, since it uses less digits than its factorization.

21051984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25827 (or 25821 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 21051984 is about 4588.2441085888. The cubic root of 21051984 is about 276.1198807095.

Adding to 21051984 its reverse (48915012), we get a palindrome (69966996).

The spelling of 21051984 in words is "twenty-one million, fifty-one thousand, nine hundred eighty-four".