21113784 has 48 divisors (see below), whose sum is σ = 59306520. Its totient is φ = 7037280.

The previous prime is 21113783. The next prime is 21113797. The reversal of 21113784 is 48731112.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21113783) 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 11 ways as a sum of consecutive naturals, for example, 3487 + ... + 7374.

Almost surely, 2^21113784 is an apocalyptic number.

21113784 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21113784 is an abundant number, since it is smaller than the sum of its proper divisors (38192736).

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

21113784 is a wasteful number, since it uses less digits than its factorization.

21113784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10882 (or 10866 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 21113784 is about 4594.9737757685. The cubic root of 21113784 is about 276.3898083635.

Adding to 21113784 its reverse (48731112), we get a palindrome (69844896).

The spelling of 21113784 in words is "twenty-one million, one hundred thirteen thousand, seven hundred eighty-four".