669807978 has 128 divisors (see below), whose sum is σ = 1654456320. Its totient is φ = 176679360.

The previous prime is 669807977. The next prime is 669808019. The reversal of 669807978 is 879708966.

It is not an unprimeable number, because it can be changed into a prime (669807977) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5112973 + ... + 5113103.

It is an arithmetic number, because the mean of its divisors is an integer number (12925440).

Almost surely, 2^669807978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 669807978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (827228160).

669807978 is an abundant number, since it is smaller than the sum of its proper divisors (984648342).

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

669807978 is a wasteful number, since it uses less digits than its factorization.

669807978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312.

The product of its (nonzero) digits is 9144576, while the sum is 60.

The square root of 669807978 is about 25880.6487167536. The cubic root of 669807978 is about 874.9504093800.

The spelling of 669807978 in words is "six hundred sixty-nine million, eight hundred seven thousand, nine hundred seventy-eight".