21451512202453 has 4 divisors (see below), whose sum is σ = 21575509382988. Its totient is φ = 21327515021920.

The previous prime is 21451512202451. The next prime is 21451512202517. The reversal of 21451512202453 is 35420221515412.

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 15179883522769 + 6271628679684 = 3896137^2 + 2504322^2 .

It is a cyclic number.

It is not a de Polignac number, because 21451512202453 - 2¹ = 21451512202451 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 (21451512202451) 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, 61998590008 + ... + 61998590353.

It is an arithmetic number, because the mean of its divisors is an integer number (5393877345747).

Almost surely, 2^{21451512202453} is an apocalyptic number.

It is an amenable number.

21451512202453 is a deficient number, since it is larger than the sum of its proper divisors (123997180535).

21451512202453 is a wasteful number, since it uses less digits than its factorization.

21451512202453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123997180534.

The product of its (nonzero) digits is 96000, while the sum is 37.

Adding to 21451512202453 its reverse (35420221515412), we get a palindrome (56871733717865).

The spelling of 21451512202453 in words is "twenty-one trillion, four hundred fifty-one billion, five hundred twelve million, two hundred two thousand, four hundred fifty-three".