66626640 has 240 divisors, whose sum is σ = 239265936. Its totient is φ = 16588800.

The previous prime is 66626639. The next prime is 66626663. The reversal of 66626640 is 4662666.

66626640 is nontrivially palindromic in base 11.

It can be written as a sum of positive squares in 8 ways, for example, as 11451456 + 55175184 = 3384^2 + 7428^2 .

It is a tau number, because it is divible by the number of its divisors (240).

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

It is a junction number, because it is equal to n+sod(n) for n = 66626595 and 66626604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1092210 + ... + 1092270.

Almost surely, 2^66626640 is an apocalyptic number.

66626640 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 66626640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119632968).

66626640 is an abundant number, since it is smaller than the sum of its proper divisors (172639296).

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

66626640 is a wasteful number, since it uses less digits than its factorization.

66626640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 36.

The square root of 66626640 is about 8162.5143185173. The cubic root of 66626640 is about 405.3989667013.

The spelling of 66626640 in words is "sixty-six million, six hundred twenty-six thousand, six hundred forty".