21012320125 has 16 divisors (see below), whose sum is σ = 26359278192. Its totient is φ = 16722739200.

The previous prime is 21012320117. The next prime is 21012320143. The reversal of 21012320125 is 52102321012.

It can be written as a sum of positive squares in 8 ways, for example, as 7846593561 + 13165726564 = 88581^2 + 114742^2 .

It is not a de Polignac number, because 21012320125 - 2³ = 21012320117 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 15 ways as a sum of consecutive naturals, for example, 411364 + ... + 459613.

It is an arithmetic number, because the mean of its divisors is an integer number (1647454887).

Almost surely, 2^21012320125 is an apocalyptic number.

21012320125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21012320125 is a deficient number, since it is larger than the sum of its proper divisors (5346958067).

21012320125 is an equidigital number, since it uses as much as digits as its factorization.

21012320125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 871185 (or 871175 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

Adding to 21012320125 its reverse (52102321012), we get a palindrome (73114641137).

The spelling of 21012320125 in words is "twenty-one billion, twelve million, three hundred twenty thousand, one hundred twenty-five".