1643496985 has 16 divisors (see below), whose sum is σ = 2124864000. Its totient is φ = 1213110720.

The previous prime is 1643496977. The next prime is 1643496997. The reversal of 1643496985 is 5896943461.

It is a happy number.

It is not a de Polignac number, because 1643496985 - 2³ = 1643496977 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 190720 + ... + 199150.

It is an arithmetic number, because the mean of its divisors is an integer number (132804000).

Almost surely, 2^1643496985 is an apocalyptic number.

It is an amenable number.

1643496985 is a deficient number, since it is larger than the sum of its proper divisors (481367015).

1643496985 is a wasteful number, since it uses less digits than its factorization.

1643496985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11448.

The product of its digits is 5598720, while the sum is 55.

The square root of 1643496985 is about 40540.0664158311. The cubic root of 1643496985 is about 1180.1113044965. Note that the first 3 decimals are identical.

The spelling of 1643496985 in words is "one billion, six hundred forty-three million, four hundred ninety-six thousand, nine hundred eighty-five".