21155103125 has 72 divisors (see below), whose sum is σ = 29361042648. Its totient is φ = 15225600000.

The previous prime is 21155103113. The next prime is 21155103143. The reversal of 21155103125 is 52130155112.

It can be written as a sum of positive squares in 36 ways, for example, as 3440291716 + 17714811409 = 58654^2 + 133097^2 .

It is not a de Polignac number, because 21155103125 - 2⁶ = 21155103061 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21155103094 and 21155103103.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 21652637 + ... + 21653613.

It is an arithmetic number, because the mean of its divisors is an integer number (407792259).

Almost surely, 2^21155103125 is an apocalyptic number.

21155103125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21155103125 is a deficient number, since it is larger than the sum of its proper divisors (8205939523).

21155103125 is an frugal number, since it uses more digits than its factorization.

21155103125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1069 (or 1036 counting only the distinct ones).

The product of its (nonzero) digits is 1500, while the sum is 26.

Adding to 21155103125 its reverse (52130155112), we get a palindrome (73285258237).

The spelling of 21155103125 in words is "twenty-one billion, one hundred fifty-five million, one hundred three thousand, one hundred twenty-five".