3940400809 has 2 divisors, whose sum is σ = 3940400810. Its totient is φ = 3940400808.

The previous prime is 3940400771. The next prime is 3940400837. The reversal of 3940400809 is 9080040493.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3742013584 + 198387225 = 61172^2 + 14085^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3940400809 is a prime.

It is not a weakly prime, because it can be changed into another prime (3940400869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1970200404 + 1970200405.

It is an arithmetic number, because the mean of its divisors is an integer number (1970200405).

Almost surely, 2^3940400809 is an apocalyptic number.

It is an amenable number.

3940400809 is a deficient number, since it is larger than the sum of its proper divisors (1).

3940400809 is an equidigital number, since it uses as much as digits as its factorization.

3940400809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31104, while the sum is 37.

The square root of 3940400809 is about 62772.6119338681. The cubic root of 3940400809 is about 1579.4775831203.

The spelling of 3940400809 in words is "three billion, nine hundred forty million, four hundred thousand, eight hundred nine".