66651988 has 24 divisors (see below), whose sum is σ = 127135008. Its totient is φ = 30389856.

The previous prime is 66651979. The next prime is 66651989. The reversal of 66651988 is 88915666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66651989) 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, 3406 + ... + 12037.

It is an arithmetic number, because the mean of its divisors is an integer number (5297292).

Almost surely, 2^66651988 is an apocalyptic number.

It is an amenable number.

66651988 is a deficient number, since it is larger than the sum of its proper divisors (60483020).

66651988 is a wasteful number, since it uses less digits than its factorization.

66651988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15543 (or 15541 counting only the distinct ones).

The product of its digits is 622080, while the sum is 49.

The square root of 66651988 is about 8164.0668787070. The cubic root of 66651988 is about 405.4503713152.

The spelling of 66651988 in words is "sixty-six million, six hundred fifty-one thousand, nine hundred eighty-eight".