91428409 has 2 divisors, whose sum is σ = 91428410. Its totient is φ = 91428408.

The previous prime is 91428391. The next prime is 91428487. The reversal of 91428409 is 90482419.

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., 82446400 + 8982009 = 9080^2 + 2997^2 .

It is a cyclic number.

It is not a de Polignac number, because 91428409 - 2⁵ = 91428377 is a prime.

It is not a weakly prime, because it can be changed into another prime (91428509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45714204 + 45714205.

It is an arithmetic number, because the mean of its divisors is an integer number (45714205).

Almost surely, 2^91428409 is an apocalyptic number.

It is an amenable number.

91428409 is a deficient number, since it is larger than the sum of its proper divisors (1).

91428409 is an equidigital number, since it uses as much as digits as its factorization.

91428409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 91428409 is about 9561.8203810781. The cubic root of 91428409 is about 450.4988853973.

The spelling of 91428409 in words is "ninety-one million, four hundred twenty-eight thousand, four hundred nine".