28257121 has 2 divisors, whose sum is σ = 28257122. Its totient is φ = 28257120.

The previous prime is 28257067. The next prime is 28257137. The reversal of 28257121 is 12175282.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27447121 + 810000 = 5239^2 + 900^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28257121 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28257121.

It is not a weakly prime, because it can be changed into another prime (28257221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14128560 + 14128561.

It is an arithmetic number, because the mean of its divisors is an integer number (14128561).

Almost surely, 2^28257121 is an apocalyptic number.

It is an amenable number.

28257121 is a deficient number, since it is larger than the sum of its proper divisors (1).

28257121 is an equidigital number, since it uses as much as digits as its factorization.

28257121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2240, while the sum is 28.

The square root of 28257121 is about 5315.7427514883. The cubic root of 28257121 is about 304.5855555206.

The spelling of 28257121 in words is "twenty-eight million, two hundred fifty-seven thousand, one hundred twenty-one".