1643991480 has 192 divisors, whose sum is σ = 5560045920. Its totient is φ = 420940800.

The previous prime is 1643991421. The next prime is 1643991487. The reversal of 1643991480 is 841993461.

1643991480 is a `hidden beast` number, since 164 + 3 + 9 + 9 + 1 + 480 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1643991487) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 943410 + ... + 945150.

Almost surely, 2^1643991480 is an apocalyptic number.

1643991480 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 1643991480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2780022960).

1643991480 is an abundant number, since it is smaller than the sum of its proper divisors (3916054440).

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

1643991480 is a wasteful number, since it uses less digits than its factorization.

1643991480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1862 (or 1855 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The square root of 1643991480 is about 40546.1648001386. The cubic root of 1643991480 is about 1180.2296498352.

The spelling of 1643991480 in words is "one billion, six hundred forty-three million, nine hundred ninety-one thousand, four hundred eighty".