1643740709 has 16 divisors (see below), whose sum is σ = 1813050624. Its totient is φ = 1480939200.

The previous prime is 1643740699. The next prime is 1643740739. The reversal of 1643740709 is 9070473461.

It is a de Polignac number, because none of the positive numbers 2^k-1643740709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1643740739) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 95972 + ... + 111794.

It is an arithmetic number, because the mean of its divisors is an integer number (113315664).

Almost surely, 2^1643740709 is an apocalyptic number.

It is an amenable number.

1643740709 is a deficient number, since it is larger than the sum of its proper divisors (169309915).

1643740709 is a wasteful number, since it uses less digits than its factorization.

1643740709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16028.

The product of its (nonzero) digits is 127008, while the sum is 41.

The square root of 1643740709 is about 40543.0722688846. The cubic root of 1643740709 is about 1180.1696368682.

The spelling of 1643740709 in words is "one billion, six hundred forty-three million, seven hundred forty thousand, seven hundred nine".