66643780 has 24 divisors (see below), whose sum is σ = 159945408. Its totient is φ = 22849248.

The previous prime is 66643777. The next prime is 66643783. The reversal of 66643780 is 8734666.

It is an interprime number because it is at equal distance from previous prime (66643777) and next prime (66643783).

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (66643783) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 237874 + ... + 238153.

It is an arithmetic number, because the mean of its divisors is an integer number (6664392).

Almost surely, 2^66643780 is an apocalyptic number.

It is an amenable number.

66643780 is an abundant number, since it is smaller than the sum of its proper divisors (93301628).

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

66643780 is a wasteful number, since it uses less digits than its factorization.

66643780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 476043 (or 476041 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 40.

The square root of 66643780 is about 8163.5641725903. The cubic root of 66643780 is about 405.4337272842.

The spelling of 66643780 in words is "sixty-six million, six hundred forty-three thousand, seven hundred eighty".