21357984 has 96 divisors (see below), whose sum is σ = 62052480. Its totient is φ = 6397952.

The previous prime is 21357983. The next prime is 21357997. The reversal of 21357984 is 48975312.

It is a tau number, because it is divible by the number of its divisors (96).

It is not an unprimeable number, because it can be changed into a prime (21357983) 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 15 ways as a sum of consecutive naturals, for example, 37252 + ... + 37820.

It is an arithmetic number, because the mean of its divisors is an integer number (646380).

Almost surely, 2^21357984 is an apocalyptic number.

21357984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21357984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31026240).

21357984 is an abundant number, since it is smaller than the sum of its proper divisors (40694496).

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

21357984 is a wasteful number, since it uses less digits than its factorization.

21357984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 622 (or 614 counting only the distinct ones).

The product of its digits is 60480, while the sum is 39.

The square root of 21357984 is about 4621.4698960396. The cubic root of 21357984 is about 277.4512924820.

The spelling of 21357984 in words is "twenty-one million, three hundred fifty-seven thousand, nine hundred eighty-four".