66664257720 has 32 divisors (see below), whose sum is σ = 199992773520. Its totient is φ = 17777135360.

The previous prime is 66664257719. The next prime is 66664257749. The reversal of 66664257720 is 2775246666.

It is a happy number.

It is a hoax number, since the sum of its digits (51) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 277767621 + ... + 277767860.

Almost surely, 2^66664257720 is an apocalyptic number.

66664257720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66664257720 is an abundant number, since it is smaller than the sum of its proper divisors (133328515800).

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

66664257720 is a wasteful number, since it uses less digits than its factorization.

66664257720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 555535495 (or 555535491 counting only the distinct ones).

The product of its (nonzero) digits is 5080320, while the sum is 51.

The spelling of 66664257720 in words is "sixty-six billion, six hundred sixty-four million, two hundred fifty-seven thousand, seven hundred twenty".