66581222400 has 1584 divisors, whose sum is σ = 310441797120. Its totient is φ = 13735526400.

The previous prime is 66581222333. The next prime is 66581222413. The reversal of 66581222400 is 422218566.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (1584).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 479001531 + ... + 479001669.

Almost surely, 2^66581222400 is an apocalyptic number.

66581222400 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 66581222400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (155220898560).

66581222400 is an abundant number, since it is smaller than the sum of its proper divisors (243860574720).

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

66581222400 is a wasteful number, since it uses less digits than its factorization.

66581222400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The spelling of 66581222400 in words is "sixty-six billion, five hundred eighty-one million, two hundred twenty-two thousand, four hundred".