66666658 has 4 divisors (see below), whose sum is σ = 99999990. Its totient is φ = 33333328.

The previous prime is 66666653. The next prime is 66666667. The reversal of 66666658 is 85666666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 62773929 + 3892729 = 7923^2 + 1973^2 .

It is not an unprimeable number, because it can be changed into a prime (66666653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16666663 + ... + 16666666.

Almost surely, 2^66666658 is an apocalyptic number.

66666658 is a deficient number, since it is larger than the sum of its proper divisors (33333332).

66666658 is a wasteful number, since it uses less digits than its factorization.

66666658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33333331.

The product of its digits is 1866240, while the sum is 49.

The square root of 66666658 is about 8164.9652785545. The cubic root of 66666658 is about 405.4801154674.

The spelling of 66666658 in words is "sixty-six million, six hundred sixty-six thousand, six hundred fifty-eight".