1640445409 has 2 divisors, whose sum is σ = 1640445410. Its totient is φ = 1640445408.

The previous prime is 1640445397. The next prime is 1640445437. The reversal of 1640445409 is 9045440461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 994014784 + 646430625 = 31528^2 + 25425^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640445409 - 2⁷ = 1640445281 is a prime.

It is a super-2 number, since 2×1640445409² = 5382122279818354562, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1640440409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820222704 + 820222705.

It is an arithmetic number, because the mean of its divisors is an integer number (820222705).

Almost surely, 2^1640445409 is an apocalyptic number.

It is an amenable number.

1640445409 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640445409 is an equidigital number, since it uses as much as digits as its factorization.

1640445409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 69120, while the sum is 37.

The square root of 1640445409 is about 40502.4123849432. The cubic root of 1640445409 is about 1179.3804583149.

The spelling of 1640445409 in words is "one billion, six hundred forty million, four hundred forty-five thousand, four hundred nine".