400042309 has 2 divisors, whose sum is σ = 400042310. Its totient is φ = 400042308.

The previous prime is 400042241. The next prime is 400042319. The reversal of 400042309 is 903240004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 252905409 + 147136900 = 15903^2 + 12130^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400042309 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 400042309.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400042319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200021154 + 200021155.

It is an arithmetic number, because the mean of its divisors is an integer number (200021155).

Almost surely, 2^400042309 is an apocalyptic number.

It is an amenable number.

400042309 is a deficient number, since it is larger than the sum of its proper divisors (1).

400042309 is an equidigital number, since it uses as much as digits as its factorization.

400042309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 400042309 is about 20001.0576970319. The cubic root of 400042309 is about 736.8322767603.

The spelling of 400042309 in words is "four hundred million, forty-two thousand, three hundred nine".