21128076025 has 27 divisors (see below), whose sum is σ = 30483511821. Its totient is φ = 14484335040.

The previous prime is 21128075911. The next prime is 21128076061. The reversal of 21128076025 is 52067082112.

It is a happy number.

The square root of 21128076025 is 145355.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 11242148841 + 9885927184 = 106029^2 + 99428^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21128076025 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 5085349 + ... + 5089501.

Almost surely, 2^21128076025 is an apocalyptic number.

21128076025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21128076025 is the 145355-th square number.

21128076025 is the 72678-th centered octagonal number.

It is an amenable number.

21128076025 is a deficient number, since it is larger than the sum of its proper divisors (9355435796).

21128076025 is an frugal number, since it uses more digits than its factorization.

21128076025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8330 (or 4165 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 34.

The spelling of 21128076025 in words is "twenty-one billion, one hundred twenty-eight million, seventy-six thousand, twenty-five".