1664999640 has 96 divisors (see below), whose sum is σ = 5696074800. Its totient is φ = 420629760.

The previous prime is 1664999639. The next prime is 1664999663. The reversal of 1664999640 is 469994661.

1664999640 is a `hidden beast` number, since 1 + 66 + 499 + 96 + 4 + 0 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 114871 + ... + 128550.

Almost surely, 2^1664999640 is an apocalyptic number.

1664999640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1664999640 is an abundant number, since it is smaller than the sum of its proper divisors (4031075160).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1664999640 is a wasteful number, since it uses less digits than its factorization.

1664999640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243457 (or 243450 counting only the distinct ones).

The product of its (nonzero) digits is 2519424, while the sum is 54.

The square root of 1664999640 is about 40804.4071149184. The cubic root of 1664999640 is about 1185.2356738971.

The spelling of 1664999640 in words is "one billion, six hundred sixty-four million, nine hundred ninety-nine thousand, six hundred forty".