21453500 has 48 divisors (see below), whose sum is σ = 47410272. Its totient is φ = 8480000.

The previous prime is 21453493. The next prime is 21453529. The reversal of 21453500 is 535412.

It is a hoax number, since the sum of its digits (20) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 53300 + ... + 53700.

It is an arithmetic number, because the mean of its divisors is an integer number (987714).

Almost surely, 2^21453500 is an apocalyptic number.

21453500 is a gapful number since it is divisible by the number (20) 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 21453500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23705136).

21453500 is an abundant number, since it is smaller than the sum of its proper divisors (25956772).

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

21453500 is a wasteful number, since it uses less digits than its factorization.

21453500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527 (or 515 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 20.

The square root of 21453500 is about 4631.7923096788. The cubic root of 21453500 is about 277.8642782460.

Adding to 21453500 its reverse (535412), we get a palindrome (21988912).

The spelling of 21453500 in words is "twenty-one million, four hundred fifty-three thousand, five hundred".