66857906 has 8 divisors (see below), whose sum is σ = 106186140. Its totient is φ = 31462528.

The previous prime is 66857899. The next prime is 66857909. The reversal of 66857906 is 60975866.

It can be written as a sum of positive squares in 2 ways, for example, as 63282025 + 3575881 = 7955^2 + 1891^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (66857909) 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, 983171 + ... + 983238.

Almost surely, 2^66857906 is an apocalyptic number.

66857906 is a deficient number, since it is larger than the sum of its proper divisors (39328234).

66857906 is a wasteful number, since it uses less digits than its factorization.

66857906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1966428.

The product of its (nonzero) digits is 544320, while the sum is 47.

The square root of 66857906 is about 8176.6683924444. The cubic root of 66857906 is about 405.8674816442.

The spelling of 66857906 in words is "sixty-six million, eight hundred fifty-seven thousand, nine hundred six".