21012455125 has 16 divisors (see below), whose sum is σ = 26244936432. Its totient is φ = 16796251200.

The previous prime is 21012455119. The next prime is 21012455137. The reversal of 21012455125 is 52155421012.

It can be written as a sum of positive squares in 8 ways, for example, as 8892867204 + 12119587921 = 94302^2 + 110089^2 .

It is not a de Polignac number, because 21012455125 - 2¹⁵ = 21012422357 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21012455093 and 21012455102.

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, 86679 + ... + 222571.

It is an arithmetic number, because the mean of its divisors is an integer number (1640308527).

Almost surely, 2^21012455125 is an apocalyptic number.

21012455125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21012455125 is a deficient number, since it is larger than the sum of its proper divisors (5232481307).

21012455125 is a wasteful number, since it uses less digits than its factorization.

21012455125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137145 (or 137135 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 28.

Adding to 21012455125 its reverse (52155421012), we get a palindrome (73167876137).

The spelling of 21012455125 in words is "twenty-one billion, twelve million, four hundred fifty-five thousand, one hundred twenty-five".