1640497409 has 2 divisors, whose sum is σ = 1640497410. Its totient is φ = 1640497408.

The previous prime is 1640497367. The next prime is 1640497421. The reversal of 1640497409 is 9047940461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 918393025 + 722104384 = 30305^2 + 26872^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640497409 - 2²⁴ = 1623720193 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1640497409.

It is not a weakly prime, because it can be changed into another prime (1640497709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820248704 + 820248705.

It is an arithmetic number, because the mean of its divisors is an integer number (820248705).

Almost surely, 2^1640497409 is an apocalyptic number.

It is an amenable number.

1640497409 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640497409 is an equidigital number, since it uses as much as digits as its factorization.

1640497409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 217728, while the sum is 44.

The square root of 1640497409 is about 40503.0543169278. The cubic root of 1640497409 is about 1179.3929197955.

The spelling of 1640497409 in words is "one billion, six hundred forty million, four hundred ninety-seven thousand, four hundred nine".