400739809 has 2 divisors, whose sum is σ = 400739810. Its totient is φ = 400739808.

The previous prime is 400739789. The next prime is 400739959. The reversal of 400739809 is 908937004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 388208209 + 12531600 = 19703^2 + 3540^2 .

It is a cyclic number.

It is not a de Polignac number, because 400739809 - 2⁷ = 400739681 is a prime.

It is not a weakly prime, because it can be changed into another prime (400739309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200369904 + 200369905.

It is an arithmetic number, because the mean of its divisors is an integer number (200369905).

Almost surely, 2^400739809 is an apocalyptic number.

It is an amenable number.

400739809 is a deficient number, since it is larger than the sum of its proper divisors (1).

400739809 is an equidigital number, since it uses as much as digits as its factorization.

400739809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 400739809 is about 20018.4866810656. The cubic root of 400739809 is about 737.2602665789.

The spelling of 400739809 in words is "four hundred million, seven hundred thirty-nine thousand, eight hundred nine".