66666620 has 12 divisors (see below), whose sum is σ = 139999944. Its totient is φ = 26666640.

The previous prime is 66666569. The next prime is 66666629. The reversal of 66666620 is 2666666.

It is a super-4 number, since 4×66666620⁴ (a number of 32 digits) contains 4444 as substring.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66666629) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1666646 + ... + 1666685.

It is an arithmetic number, because the mean of its divisors is an integer number (11666662).

Almost surely, 2^66666620 is an apocalyptic number.

It is an amenable number.

66666620 is an abundant number, since it is smaller than the sum of its proper divisors (73333324).

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

66666620 is a wasteful number, since it uses less digits than its factorization.

66666620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3333340 (or 3333338 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 38.

The square root of 66666620 is about 8164.9629515387. The cubic root of 66666620 is about 405.4800384262.

The spelling of 66666620 in words is "sixty-six million, six hundred sixty-six thousand, six hundred twenty".