21523030453 has 4 divisors (see below), whose sum is σ = 21525270700. Its totient is φ = 21520790208.

The previous prime is 21523030439. The next prime is 21523030469. The reversal of 21523030453 is 35403032512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2140265169 + 19382765284 = 46263^2 + 139222^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21523030453 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 (21523030433) 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, 1105650 + ... + 1124947.

It is an arithmetic number, because the mean of its divisors is an integer number (5381317675).

Almost surely, 2^21523030453 is an apocalyptic number.

It is an amenable number.

21523030453 is a deficient number, since it is larger than the sum of its proper divisors (2240247).

21523030453 is an equidigital number, since it uses as much as digits as its factorization.

21523030453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2240246.

The product of its (nonzero) digits is 10800, while the sum is 28.

Adding to 21523030453 its reverse (35403032512), we get a palindrome (56926062965).

The spelling of 21523030453 in words is "twenty-one billion, five hundred twenty-three million, thirty thousand, four hundred fifty-three".