66899994 has 48 divisors (see below), whose sum is σ = 156356928. Its totient is φ = 19027008.

The previous prime is 66899983. The next prime is 66899999. The reversal of 66899994 is 49999866.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (66899999) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 91659 + ... + 92385.

It is an arithmetic number, because the mean of its divisors is an integer number (3257436).

Almost surely, 2^66899994 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66899994, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78178464).

66899994 is an abundant number, since it is smaller than the sum of its proper divisors (89456934).

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

66899994 is a wasteful number, since it uses less digits than its factorization.

66899994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1059 (or 1052 counting only the distinct ones).

The product of its digits is 7558272, while the sum is 60.

The square root of 66899994 is about 8179.2416518893. The cubic root of 66899994 is about 405.9526302245.

The spelling of 66899994 in words is "sixty-six million, eight hundred ninety-nine thousand, nine hundred ninety-four".