66994278 has 32 divisors (see below), whose sum is σ = 145453056. Its totient is φ = 20448288.

The previous prime is 66994273. The next prime is 66994303. The reversal of 66994278 is 87249966.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 66994278.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66994273) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6525 + ... + 13287.

It is an arithmetic number, because the mean of its divisors is an integer number (4545408).

Almost surely, 2^66994278 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66994278, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (72726528).

66994278 is an abundant number, since it is smaller than the sum of its proper divisors (78458778).

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

66994278 is a wasteful number, since it uses less digits than its factorization.

66994278 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6908.

The product of its digits is 1306368, while the sum is 51.

The square root of 66994278 is about 8185.0032376292. The cubic root of 66994278 is about 406.1432474377.

The spelling of 66994278 in words is "sixty-six million, nine hundred ninety-four thousand, two hundred seventy-eight".