28131409 has 2 divisors, whose sum is σ = 28131410. Its totient is φ = 28131408.

The previous prime is 28131401. The next prime is 28131449. The reversal of 28131409 is 90413182.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27878400 + 253009 = 5280^2 + 503^2 .

It is a cyclic number.

It is not a de Polignac number, because 28131409 - 2³ = 28131401 is a prime.

It is not a weakly prime, because it can be changed into another prime (28131401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14065704 + 14065705.

It is an arithmetic number, because the mean of its divisors is an integer number (14065705).

Almost surely, 2^28131409 is an apocalyptic number.

It is an amenable number.

28131409 is a deficient number, since it is larger than the sum of its proper divisors (1).

28131409 is an equidigital number, since it uses as much as digits as its factorization.

28131409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 28131409 is about 5303.9050707945. The cubic root of 28131409 is about 304.1331977769.

The spelling of 28131409 in words is "twenty-eight million, one hundred thirty-one thousand, four hundred nine".