1644136409 has 2 divisors, whose sum is σ = 1644136410. Its totient is φ = 1644136408.

The previous prime is 1644136399. The next prime is 1644136457. The reversal of 1644136409 is 9046314461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1643491600 + 644809 = 40540^2 + 803^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1644136409 is a prime.

It is a super-3 number, since 3×1644136409³ (a number of 29 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (1644136009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822068204 + 822068205.

It is an arithmetic number, because the mean of its divisors is an integer number (822068205).

Almost surely, 2^1644136409 is an apocalyptic number.

It is an amenable number.

1644136409 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644136409 is an equidigital number, since it uses as much as digits as its factorization.

1644136409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 62208, while the sum is 38.

The square root of 1644136409 is about 40547.9519704756. The cubic root of 1644136409 is about 1180.2643305658.

The spelling of 1644136409 in words is "one billion, six hundred forty-four million, one hundred thirty-six thousand, four hundred nine".