1663791640 has 32 divisors (see below), whose sum is σ = 4278322080. Its totient is φ = 570442752.

The previous prime is 1663791629. The next prime is 1663791659. The reversal of 1663791640 is 461973661.

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2970777 + ... + 2971336.

It is an arithmetic number, because the mean of its divisors is an integer number (133697565).

Almost surely, 2^1663791640 is an apocalyptic number.

1663791640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1663791640 is an abundant number, since it is smaller than the sum of its proper divisors (2614530440).

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

1663791640 is a wasteful number, since it uses less digits than its factorization.

1663791640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5942131 (or 5942127 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 43.

The square root of 1663791640 is about 40789.6021064192. The cubic root of 1663791640 is about 1184.9489649073.

The spelling of 1663791640 in words is "one billion, six hundred sixty-three million, seven hundred ninety-one thousand, six hundred forty".