1664430387840 has 768 divisors, whose sum is σ = 6820659216000. Its totient is φ = 382252400640.

The previous prime is 1664430387839. The next prime is 1664430387857. The reversal of 1664430387840 is 487830344661.

1664430387840 is a `hidden beast` number, since 1 + 66 + 443 + 0 + 38 + 78 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

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, 39705772 + ... + 39747668.

Almost surely, 2^{1664430387840} is an apocalyptic number.

1664430387840 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 1664430387840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3410329608000).

1664430387840 is an abundant number, since it is smaller than the sum of its proper divisors (5156228828160).

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

1664430387840 is a wasteful number, since it uses less digits than its factorization.

1664430387840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41966 (or 41937 counting only the distinct ones).

The product of its (nonzero) digits is 9289728, while the sum is 54.

The spelling of 1664430387840 in words is "one trillion, six hundred sixty-four billion, four hundred thirty million, three hundred eighty-seven thousand, eight hundred forty".