1664737920 has 320 divisors, whose sum is σ = 6298122600. Its totient is φ = 417595392.

The previous prime is 1664737891. The next prime is 1664737939. The reversal of 1664737920 is 297374661.

It can be written as a sum of positive squares in 4 ways, for example, as 1494904896 + 169833024 = 38664^2 + 13032^2 .

It is a tau number, because it is divible by the number of its divisors (320).

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 880336 + ... + 882224.

Almost surely, 2^1664737920 is an apocalyptic number.

1664737920 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 1664737920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3149061300).

1664737920 is an abundant number, since it is smaller than the sum of its proper divisors (4633384680).

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

1664737920 is a wasteful number, since it uses less digits than its factorization.

1664737920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1937 (or 1916 counting only the distinct ones).

The product of its (nonzero) digits is 381024, while the sum is 45.

The square root of 1664737920 is about 40801.1999823535. The cubic root of 1664737920 is about 1185.1735685513.

The spelling of 1664737920 in words is "one billion, six hundred sixty-four million, seven hundred thirty-seven thousand, nine hundred twenty".