21530453 has 16 divisors (see below), whose sum is σ = 25737600. Its totient is φ = 17992800.

The previous prime is 21530447. The next prime is 21530459. The reversal of 21530453 is 35403512.

It is an interprime number because it is at equal distance from previous prime (21530447) and next prime (21530459).

It is not a de Polignac number, because 21530453 - 2⁶ = 21530389 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530459) 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, 13298 + ... + 14828.

It is an arithmetic number, because the mean of its divisors is an integer number (1608600).

Almost surely, 2^21530453 is an apocalyptic number.

It is an amenable number.

21530453 is a deficient number, since it is larger than the sum of its proper divisors (4207147).

21530453 is an equidigital number, since it uses as much as digits as its factorization.

21530453 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1593 (or 1579 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 23.

The square root of 21530453 is about 4640.0919171930. The cubic root of 21530453 is about 278.1961118168.

Adding to 21530453 its reverse (35403512), we get a palindrome (56933965).

The spelling of 21530453 in words is "twenty-one million, five hundred thirty thousand, four hundred fifty-three".