28134721 has 2 divisors, whose sum is σ = 28134722. Its totient is φ = 28134720.

The previous prime is 28134719. The next prime is 28134737. The reversal of 28134721 is 12743182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19044496 + 9090225 = 4364^2 + 3015^2 .

It is a cyclic number.

It is not a de Polignac number, because 28134721 - 2¹ = 28134719 is a prime.

Together with 28134719, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28134721.

It is not a weakly prime, because it can be changed into another prime (28134751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14067360 + 14067361.

It is an arithmetic number, because the mean of its divisors is an integer number (14067361).

Almost surely, 2^28134721 is an apocalyptic number.

It is an amenable number.

28134721 is a deficient number, since it is larger than the sum of its proper divisors (1).

28134721 is an equidigital number, since it uses as much as digits as its factorization.

28134721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 28.

The square root of 28134721 is about 5304.2172843880. The cubic root of 28134721 is about 304.1451328305.

The spelling of 28134721 in words is "twenty-eight million, one hundred thirty-four thousand, seven hundred twenty-one".