21506211314125 has 8 divisors (see below), whose sum is σ = 26839751720184. Its totient is φ = 17204969051200.

The previous prime is 21506211314111. The next prime is 21506211314131. The reversal of 21506211314125 is 52141311260512.

It can be written as a sum of positive squares in 4 ways, for example, as 3463179565444 + 18043031748681 = 1860962^2 + 4247709^2 .

It is not a de Polignac number, because 21506211314125 - 2¹¹ = 21506211312077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 86024845132 + ... + 86024845381.

It is an arithmetic number, because the mean of its divisors is an integer number (3354968965023).

Almost surely, 2^{21506211314125} is an apocalyptic number.

21506211314125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21506211314125 is a deficient number, since it is larger than the sum of its proper divisors (5333540406059).

21506211314125 is an equidigital number, since it uses as much as digits as its factorization.

21506211314125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172049690528 (or 172049690518 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 34.

Adding to 21506211314125 its reverse (52141311260512), we get a palindrome (73647522574637).

The spelling of 21506211314125 in words is "twenty-one trillion, five hundred six billion, two hundred eleven million, three hundred fourteen thousand, one hundred twenty-five".