28731709 has 2 divisors, whose sum is σ = 28731710. Its totient is φ = 28731708.

The previous prime is 28731707. The next prime is 28731713. The reversal of 28731709 is 90713782.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25502500 + 3229209 = 5050^2 + 1797^2 .

It is a cyclic number.

It is not a de Polignac number, because 28731709 - 2¹ = 28731707 is a prime.

It is a super-2 number, since 2×28731709² = 1651022204121362, which contains 22 as substring.

Together with 28731707, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28731701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14365854 + 14365855.

It is an arithmetic number, because the mean of its divisors is an integer number (14365855).

Almost surely, 2^28731709 is an apocalyptic number.

It is an amenable number.

28731709 is a deficient number, since it is larger than the sum of its proper divisors (1).

28731709 is an equidigital number, since it uses as much as digits as its factorization.

28731709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 28731709 is about 5360.1967314642. The cubic root of 28731709 is about 306.2813032559.

The spelling of 28731709 in words is "twenty-eight million, seven hundred thirty-one thousand, seven hundred nine".