1645408332820 has 192 divisors, whose sum is σ = 4237108807680. Its totient is φ = 523874377728.

The previous prime is 1645408332809. The next prime is 1645408332829. The reversal of 1645408332820 is 282338045461.

It is a super-3 number, since 3×1645408332820³ (a number of 38 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645408332829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 465723774 + ... + 465727306.

It is an arithmetic number, because the mean of its divisors is an integer number (22068275040).

Almost surely, 2^{1645408332820} is an apocalyptic number.

1645408332820 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 1645408332820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2118554403840).

1645408332820 is an abundant number, since it is smaller than the sum of its proper divisors (2591700474860).

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

1645408332820 is a wasteful number, since it uses less digits than its factorization.

1645408332820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6122 (or 6120 counting only the distinct ones).

The product of its (nonzero) digits is 1105920, while the sum is 46.

The spelling of 1645408332820 in words is "one trillion, six hundred forty-five billion, four hundred eight million, three hundred thirty-two thousand, eight hundred twenty".