21515131442225 has 12 divisors (see below), whose sum is σ = 26694157596636. Its totient is φ = 17202173148480.

The previous prime is 21515131442141. The next prime is 21515131442239. The reversal of 21515131442225 is 52224413151512.

It can be written as a sum of positive squares in 6 ways, for example, as 852724811761 + 20662406630464 = 923431^2 + 4545592^2 .

It is not a de Polignac number, because 21515131442225 - 2⁴⁰ = 20415619814449 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 248255942 + ... + 248342591.

It is an arithmetic number, because the mean of its divisors is an integer number (2224513133053).

Almost surely, 2^{21515131442225} is an apocalyptic number.

21515131442225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21515131442225 is a deficient number, since it is larger than the sum of its proper divisors (5179026154411).

21515131442225 is a wasteful number, since it uses less digits than its factorization.

21515131442225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 496600276 (or 496600271 counting only the distinct ones).

The product of its digits is 96000, while the sum is 38.

Adding to 21515131442225 its reverse (52224413151512), we get a palindrome (73739544593737).

The spelling of 21515131442225 in words is "twenty-one trillion, five hundred fifteen billion, one hundred thirty-one million, four hundred forty-two thousand, two hundred twenty-five".