698640809 has 2 divisors, whose sum is σ = 698640810. Its totient is φ = 698640808.

The previous prime is 698640793. The next prime is 698640829. The reversal of 698640809 is 908046896.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 463110400 + 235530409 = 21520^2 + 15347^2 .

It is a cyclic number.

It is not a de Polignac number, because 698640809 - 2⁴ = 698640793 is a prime.

It is not a weakly prime, because it can be changed into another prime (698640829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 349320404 + 349320405.

It is an arithmetic number, because the mean of its divisors is an integer number (349320405).

Almost surely, 2^698640809 is an apocalyptic number.

It is an amenable number.

698640809 is a deficient number, since it is larger than the sum of its proper divisors (1).

698640809 is an equidigital number, since it uses as much as digits as its factorization.

698640809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 746496, while the sum is 50.

The square root of 698640809 is about 26431.8143342450. The cubic root of 698640809 is about 887.3289478980.

The spelling of 698640809 in words is "six hundred ninety-eight million, six hundred forty thousand, eight hundred nine".