1666451435520 has 832 divisors, whose sum is σ = 5812595712000. Its totient is φ = 406412328960.

The previous prime is 1666451435449. The next prime is 1666451435533. The reversal of 1666451435520 is 255341546661.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 1666451435520.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4774932306 + ... + 4774932654.

Almost surely, 2^{1666451435520} is an apocalyptic number.

1666451435520 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 1666451435520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2906297856000).

1666451435520 is an abundant number, since it is smaller than the sum of its proper divisors (4146144276480).

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

1666451435520 is a wasteful number, since it uses less digits than its factorization.

1666451435520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 544 (or 522 counting only the distinct ones).

The product of its (nonzero) digits is 2592000, while the sum is 48.

The spelling of 1666451435520 in words is "one trillion, six hundred sixty-six billion, four hundred fifty-one million, four hundred thirty-five thousand, five hundred twenty".