1643658660 has 288 divisors, whose sum is σ = 6088642560. Its totient is φ = 350735616.

The previous prime is 1643658629. The next prime is 1643658677. The reversal of 1643658660 is 668563461.

1643658660 is a `hidden beast` number, since 1 + 6 + 4 + 3 + 6 + 586 + 60 = 666.

1643658660 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×1643658660² = 5403227581185991200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1245481 + ... + 1246799.

It is an arithmetic number, because the mean of its divisors is an integer number (21141120).

Almost surely, 2^1643658660 is an apocalyptic number.

1643658660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1643658660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3044321280).

1643658660 is an abundant number, since it is smaller than the sum of its proper divisors (4444983900).

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

1643658660 is a wasteful number, since it uses less digits than its factorization.

1643658660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1407 (or 1402 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 45.

The square root of 1643658660 is about 40542.0603817813. The cubic root of 1643658660 is about 1180.1500000830.

The spelling of 1643658660 in words is "one billion, six hundred forty-three million, six hundred fifty-eight thousand, six hundred sixty".