66615640 has 64 divisors (see below), whose sum is σ = 184484160. Its totient is φ = 21081600.

The previous prime is 66615629. The next prime is 66615641. The reversal of 66615640 is 4651666.

It is a junction number, because it is equal to n+sod(n) for n = 66615596 and 66615605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66615641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5511 + ... + 12790.

It is an arithmetic number, because the mean of its divisors is an integer number (2882565).

Almost surely, 2^66615640 is an apocalyptic number.

It is an amenable number.

66615640 is an abundant number, since it is smaller than the sum of its proper divisors (117868520).

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

66615640 is a wasteful number, since it uses less digits than its factorization.

66615640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18332 (or 18328 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 66615640 is about 8161.8404787156. The cubic root of 66615640 is about 405.3766551351.

The spelling of 66615640 in words is "sixty-six million, six hundred fifteen thousand, six hundred forty".