25528028021 has 2 divisors, whose sum is σ = 25528028022. Its totient is φ = 25528028020.

The previous prime is 25528028017. The next prime is 25528028023. The reversal of 25528028021 is 12082082552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19765548100 + 5762479921 = 140590^2 + 75911^2 .

It is a cyclic number.

It is not a de Polignac number, because 25528028021 - 2² = 25528028017 is a prime.

It is a super-2 number, since 2×25528028021² (a number of 22 digits) contains 22 as substring.

Together with 25528028023, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25528028023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12764014010 + 12764014011.

It is an arithmetic number, because the mean of its divisors is an integer number (12764014011).

Almost surely, 2^25528028021 is an apocalyptic number.

It is an amenable number.

25528028021 is a deficient number, since it is larger than the sum of its proper divisors (1).

25528028021 is an equidigital number, since it uses as much as digits as its factorization.

25528028021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25600, while the sum is 35.

The spelling of 25528028021 in words is "twenty-five billion, five hundred twenty-eight million, twenty-eight thousand, twenty-one".