66638315520 has 608 divisors, whose sum is σ = 271790380800. Its totient is φ = 15174991872.

The previous prime is 66638315507. The next prime is 66638315543. The reversal of 66638315520 is 2551383666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 247725946 + ... + 247726214.

Almost surely, 2^66638315520 is an apocalyptic number.

66638315520 is a gapful number since it is divisible by the number (60) 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 66638315520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135895190400).

66638315520 is an abundant number, since it is smaller than the sum of its proper divisors (205152065280).

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

66638315520 is an frugal number, since it uses more digits than its factorization.

66638315520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 326 (or 286 counting only the distinct ones).

The product of its (nonzero) digits is 777600, while the sum is 45.

The spelling of 66638315520 in words is "sixty-six billion, six hundred thirty-eight million, three hundred fifteen thousand, five hundred twenty".