66999766 has 4 divisors (see below), whose sum is σ = 100499652. Its totient is φ = 33499882.

The previous prime is 66999733. The next prime is 66999767. The reversal of 66999766 is 66799966.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66799966 = 2 ⋅33399983.

It is a self number, because there is not a number n which added to its sum of digits gives 66999766.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66999767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16749940 + ... + 16749943.

It is an arithmetic number, because the mean of its divisors is an integer number (25124913).

Almost surely, 2^66999766 is an apocalyptic number.

66999766 is a deficient number, since it is larger than the sum of its proper divisors (33499886).

66999766 is a wasteful number, since it uses less digits than its factorization.

66999766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33499885.

The product of its digits is 6613488, while the sum is 58.

The square root of 66999766 is about 8185.3384780350. The cubic root of 66999766 is about 406.1543372071.

The spelling of 66999766 in words is "sixty-six million, nine hundred ninety-nine thousand, seven hundred sixty-six".