28697821 has 2 divisors, whose sum is σ = 28697822. Its totient is φ = 28697820.

The previous prime is 28697803. The next prime is 28697839. The reversal of 28697821 is 12879682.

It is a balanced prime because it is at equal distance from previous prime (28697803) and next prime (28697839).

It can be written as a sum of positive squares in only one way, i.e., 21483225 + 7214596 = 4635^2 + 2686^2 .

It is a cyclic number.

It is not a de Polignac number, because 28697821 - 2⁵ = 28697789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28697861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14348910 + 14348911.

It is an arithmetic number, because the mean of its divisors is an integer number (14348911).

Almost surely, 2^28697821 is an apocalyptic number.

It is an amenable number.

28697821 is a deficient number, since it is larger than the sum of its proper divisors (1).

28697821 is an equidigital number, since it uses as much as digits as its factorization.

28697821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96768, while the sum is 43.

The square root of 28697821 is about 5357.0347208134. The cubic root of 28697821 is about 306.1608400175.

The spelling of 28697821 in words is "twenty-eight million, six hundred ninety-seven thousand, eight hundred twenty-one".