66400220400 has 60 divisors (see below), whose sum is σ = 212702043192. Its totient is φ = 17706725120.

The previous prime is 66400220371. The next prime is 66400220407. The reversal of 66400220400 is 402200466.

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66400220407) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27665559 + ... + 27667958.

Almost surely, 2^66400220400 is an apocalyptic number.

66400220400 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66400220400 is an abundant number, since it is smaller than the sum of its proper divisors (146301822792).

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

66400220400 is a wasteful number, since it uses less digits than its factorization.

66400220400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55333538 (or 55333527 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

Adding to 66400220400 its reverse (402200466), we get a palindrome (66802420866).

The spelling of 66400220400 in words is "sixty-six billion, four hundred million, two hundred twenty thousand, four hundred".