28621709 has 2 divisors, whose sum is σ = 28621710. Its totient is φ = 28621708.

The previous prime is 28621699. The next prime is 28621717. The reversal of 28621709 is 90712682.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27008809 + 1612900 = 5197^2 + 1270^2 .

It is a cyclic number.

It is not a de Polignac number, because 28621709 - 2¹⁶ = 28556173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28621759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14310854 + 14310855.

It is an arithmetic number, because the mean of its divisors is an integer number (14310855).

Almost surely, 2^28621709 is an apocalyptic number.

It is an amenable number.

28621709 is a deficient number, since it is larger than the sum of its proper divisors (1).

28621709 is an equidigital number, since it uses as much as digits as its factorization.

28621709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 28621709 is about 5349.9260742556. The cubic root of 28621709 is about 305.8899350692.

The spelling of 28621709 in words is "twenty-eight million, six hundred twenty-one thousand, seven hundred nine".