1664273439920 has 480 divisors, whose sum is σ = 4977555541056. Its totient is φ = 512638156800.

The previous prime is 1664273439911. The next prime is 1664273439929. The reversal of 1664273439920 is 299343724661.

It is an interprime number because it is at equal distance from previous prime (1664273439911) and next prime (1664273439929).

It is a Harshad number since it is a multiple of its sum of digits (56).

It is not an unprimeable number, because it can be changed into a prime (1664273439929) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1289134475 + ... + 1289135765.

Almost surely, 2^{1664273439920} is an apocalyptic number.

1664273439920 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 1664273439920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2488777770528).

1664273439920 is an abundant number, since it is smaller than the sum of its proper divisors (3313282101136).

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

1664273439920 is a wasteful number, since it uses less digits than its factorization.

1664273439920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1989 (or 1976 counting only the distinct ones).

The product of its (nonzero) digits is 11757312, while the sum is 56.

The spelling of 1664273439920 in words is "one trillion, six hundred sixty-four billion, two hundred seventy-three million, four hundred thirty-nine thousand, nine hundred twenty".