1643257249920 has 2304 divisors, whose sum is σ = 7264598140800. Its totient is φ = 338146099200.

The previous prime is 1643257249913. The next prime is 1643257249967. The reversal of 1643257249920 is 299427523461.

It is a happy number.

1643257249920 is a `hidden beast` number, since 1 + 6 + 4 + 3 + 2 + 572 + 49 + 9 + 20 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 8341407262 + ... + 8341407458.

Almost surely, 2^{1643257249920} is an apocalyptic number.

1643257249920 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 1643257249920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3632299070400).

1643257249920 is an abundant number, since it is smaller than the sum of its proper divisors (5621340890880).

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

1643257249920 is a wasteful number, since it uses less digits than its factorization.

1643257249920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319 (or 291 counting only the distinct ones).

The product of its (nonzero) digits is 6531840, while the sum is 54.

The spelling of 1643257249920 in words is "one trillion, six hundred forty-three billion, two hundred fifty-seven million, two hundred forty-nine thousand, nine hundred twenty".