21545453 has 4 divisors (see below), whose sum is σ = 21557088. Its totient is φ = 21533820.

The previous prime is 21545441. The next prime is 21545471. The reversal of 21545453 is 35454512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21545453 - 2¹⁴ = 21529069 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a zygodrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21545473) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2351 + ... + 6972.

It is an arithmetic number, because the mean of its divisors is an integer number (5389272).

Almost surely, 2^21545453 is an apocalyptic number.

It is an amenable number.

21545453 is a deficient number, since it is larger than the sum of its proper divisors (11635).

21545453 is an equidigital number, since it uses as much as digits as its factorization.

21545453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11634.

The product of its digits is 12000, while the sum is 29.

The square root of 21545453 is about 4641.7079830597. The cubic root of 21545453 is about 278.2607020815.

Adding to 21545453 its reverse (35454512), we get a palindrome (56999965).

The spelling of 21545453 in words is "twenty-one million, five hundred forty-five thousand, four hundred fifty-three".