66121404240 has 80 divisors (see below), whose sum is σ = 205254273600. Its totient is φ = 17608467456.

The previous prime is 66121404229. The next prime is 66121404247. The reversal of 66121404240 is 4240412166.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 66121404198 and 66121404207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66121404247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9045 + ... + 363764.

It is an arithmetic number, because the mean of its divisors is an integer number (2565678420).

Almost surely, 2^66121404240 is an apocalyptic number.

66121404240 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 66121404240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (102627136800).

66121404240 is an abundant number, since it is smaller than the sum of its proper divisors (139132869360).

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

66121404240 is a wasteful number, since it uses less digits than its factorization.

66121404240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 373564 (or 373558 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

The spelling of 66121404240 in words is "sixty-six billion, one hundred twenty-one million, four hundred four thousand, two hundred forty".