1640644661760 has 1280 divisors, whose sum is σ = 6147506534400. Its totient is φ = 369876271104.

The previous prime is 1640644661753. The next prime is 1640644661801. The reversal of 1640644661760 is 671664460461.

It is a tau number, because it is divible by the number of its divisors (1280).

It is a super-3 number, since 3×1640644661760³ (a number of 38 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 11975508412 + ... + 11975508548.

It is an arithmetic number, because the mean of its divisors is an integer number (4802739480).

Almost surely, 2^{1640644661760} is an apocalyptic number.

1640644661760 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 1640644661760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3073753267200).

1640644661760 is an abundant number, since it is smaller than the sum of its proper divisors (4506861872640).

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

1640644661760 is a wasteful number, since it uses less digits than its factorization.

1640644661760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 361 (or 345 counting only the distinct ones).

The product of its (nonzero) digits is 3483648, while the sum is 51.

The spelling of 1640644661760 in words is "one trillion, six hundred forty billion, six hundred forty-four million, six hundred sixty-one thousand, seven hundred sixty".