21504302505451 has 4 divisors (see below), whose sum is σ = 21504339815904. Its totient is φ = 21504265195000.

The previous prime is 21504302505449. The next prime is 21504302505509. The reversal of 21504302505451 is 15450520340512.

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

It is a cyclic number.

It is not a de Polignac number, because 21504302505451 - 2¹ = 21504302505449 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21504302505451.

It is not an unprimeable number, because it can be changed into a prime (21504302505421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17776900 + ... + 18948001.

It is an arithmetic number, because the mean of its divisors is an integer number (5376084953976).

Almost surely, 2^{21504302505451} is an apocalyptic number.

21504302505451 is a deficient number, since it is larger than the sum of its proper divisors (37310453).

21504302505451 is an equidigital number, since it uses as much as digits as its factorization.

21504302505451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37310452.

The product of its (nonzero) digits is 120000, while the sum is 37.

Adding to 21504302505451 its reverse (15450520340512), we get a palindrome (36954822845963).

The spelling of 21504302505451 in words is "twenty-one trillion, five hundred four billion, three hundred two million, five hundred five thousand, four hundred fifty-one".