21515452125305 has 4 divisors (see below), whose sum is σ = 25818542550372. Its totient is φ = 17212361700240.

The previous prime is 21515452125247. The next prime is 21515452125331. The reversal of 21515452125305 is 50352125451512.

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 14699525328016 + 6815926797289 = 3833996^2 + 2610733^2 .

It is not a de Polignac number, because 21515452125305 - 2⁸ = 21515452125049 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2151545212526 + ... + 2151545212535.

It is an arithmetic number, because the mean of its divisors is an integer number (6454635637593).

Almost surely, 2^{21515452125305} is an apocalyptic number.

It is an amenable number.

21515452125305 is a deficient number, since it is larger than the sum of its proper divisors (4303090425067).

21515452125305 is an equidigital number, since it uses as much as digits as its factorization.

21515452125305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4303090425066.

The product of its (nonzero) digits is 300000, while the sum is 41.

Adding to 21515452125305 its reverse (50352125451512), we get a palindrome (71867577576817).

The spelling of 21515452125305 in words is "twenty-one trillion, five hundred fifteen billion, four hundred fifty-two million, one hundred twenty-five thousand, three hundred five".