66681984 has 32 divisors (see below), whose sum is σ = 177125040. Its totient is φ = 22227200.

The previous prime is 66681983. The next prime is 66681997. The reversal of 66681984 is 48918666.

It is a tau number, because it is divible by the number of its divisors (32).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (66681983) 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, 86442 + ... + 87209.

Almost surely, 2^66681984 is an apocalyptic number.

66681984 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

66681984 is an abundant number, since it is smaller than the sum of its proper divisors (110443056).

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

66681984 is a wasteful number, since it uses less digits than its factorization.

66681984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173668 (or 173656 counting only the distinct ones).

The product of its digits is 497664, while the sum is 48.

The square root of 66681984 is about 8165.9037466774. The cubic root of 66681984 is about 405.5111850320.

The spelling of 66681984 in words is "sixty-six million, six hundred eighty-one thousand, nine hundred eighty-four".