21307453 has 4 divisors (see below), whose sum is σ = 22233888. Its totient is φ = 20381020.

The previous prime is 21307441. The next prime is 21307457. The reversal of 21307453 is 35470312.

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.

It is a cyclic number.

It is not a de Polignac number, because 21307453 - 2⁵ = 21307421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21307457) 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, 463183 + ... + 463228.

It is an arithmetic number, because the mean of its divisors is an integer number (5558472).

Almost surely, 2^21307453 is an apocalyptic number.

21307453 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21307453 is a deficient number, since it is larger than the sum of its proper divisors (926435).

21307453 is an equidigital number, since it uses as much as digits as its factorization.

21307453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 926434.

The product of its (nonzero) digits is 2520, while the sum is 25.

The square root of 21307453 is about 4615.9996750433. Note that the first 3 decimals coincide. The cubic root of 21307453 is about 277.2323117267.

Adding to 21307453 its reverse (35470312), we get a palindrome (56777765).

The spelling of 21307453 in words is "twenty-one million, three hundred seven thousand, four hundred fifty-three".