21453504 has 56 divisors (see below), whose sum is σ = 58734960. Its totient is φ = 6902784.

The previous prime is 21453493. The next prime is 21453529. The reversal of 21453504 is 40535412.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 3642 + ... + 7494.

Almost surely, 2^21453504 is an apocalyptic number.

21453504 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 21453504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29367480).

21453504 is an abundant number, since it is smaller than the sum of its proper divisors (37281456).

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

21453504 is a wasteful number, since it uses less digits than its factorization.

21453504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3897 (or 3887 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 21453504 is about 4631.7927414771. The cubic root of 21453504 is about 277.8642955152.

Adding to 21453504 its reverse (40535412), we get a palindrome (61988916).

The spelling of 21453504 in words is "twenty-one million, four hundred fifty-three thousand, five hundred four".