66813690 has 64 divisors (see below), whose sum is σ = 169827840. Its totient is φ = 16776000.

The previous prime is 66813679. The next prime is 66813707. The reversal of 66813690 is 9631866.

It is a happy number.

It is a super-2 number, since 2×66813690² = 8928138342832200, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 142837 + ... + 143303.

It is an arithmetic number, because the mean of its divisors is an integer number (2653560).

Almost surely, 2^66813690 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66813690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (84913920).

66813690 is an abundant number, since it is smaller than the sum of its proper divisors (103014150).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66813690 is a wasteful number, since it uses less digits than its factorization.

66813690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 747.

The product of its (nonzero) digits is 46656, while the sum is 39.

The square root of 66813690 is about 8173.9641545581. The cubic root of 66813690 is about 405.7779893900. Note that the first 3 decimals are identical.

The spelling of 66813690 in words is "sixty-six million, eight hundred thirteen thousand, six hundred ninety".