66657987 has 12 divisors (see below), whose sum is σ = 105036984. Its totient is φ = 40398720.

The previous prime is 66657973. The next prime is 66657991. The reversal of 66657987 is 78975666.

It is a happy number.

It is not a de Polignac number, because 66657987 - 2⁷ = 66657859 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66657937) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 336558 + ... + 336755.

It is an arithmetic number, because the mean of its divisors is an integer number (8753082).

Almost surely, 2^66657987 is an apocalyptic number.

66657987 is a deficient number, since it is larger than the sum of its proper divisors (38378997).

66657987 is a wasteful number, since it uses less digits than its factorization.

66657987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 673330 (or 673327 counting only the distinct ones).

The product of its digits is 3810240, while the sum is 54.

The square root of 66657987 is about 8164.4342731141. The cubic root of 66657987 is about 405.4625351125.

It can be divided in two parts, 666579 and 87, that added together give a palindrome (666666).

The spelling of 66657987 in words is "sixty-six million, six hundred fifty-seven thousand, nine hundred eighty-seven".