1649940865 has 8 divisors (see below), whose sum is σ = 2096395560. Its totient is φ = 1242308352.

The previous prime is 1649940823. The next prime is 1649940881. The reversal of 1649940865 is 5680499461.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 62157456 + 1587783409 = 7884^2 + 39847^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1649940865 - 2⁹ = 1649940353 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9705450 + ... + 9705619.

It is an arithmetic number, because the mean of its divisors is an integer number (262049445).

Almost surely, 2^1649940865 is an apocalyptic number.

It is an amenable number.

1649940865 is a deficient number, since it is larger than the sum of its proper divisors (446454695).

1649940865 is a wasteful number, since it uses less digits than its factorization.

1649940865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19411091.

The product of its (nonzero) digits is 1866240, while the sum is 52.

The square root of 1649940865 is about 40619.4641151259. The cubic root of 1649940865 is about 1181.6516335707.

The spelling of 1649940865 in words is "one billion, six hundred forty-nine million, nine hundred forty thousand, eight hundred sixty-five".