651666978 has 64 divisors (see below), whose sum is σ = 1559923200. Its totient is φ = 200990160.

The previous prime is 651666943. The next prime is 651667019. The reversal of 651666978 is 879666156.

651666978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (54).

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, 36733 + ... + 51503.

It is an arithmetic number, because the mean of its divisors is an integer number (24373800).

Almost surely, 2^651666978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 651666978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (779961600).

651666978 is an abundant number, since it is smaller than the sum of its proper divisors (908256222).

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

651666978 is a wasteful number, since it uses less digits than its factorization.

651666978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14844 (or 14838 counting only the distinct ones).

The product of its digits is 3265920, while the sum is 54.

The square root of 651666978 is about 25527.7687626631. The cubic root of 651666978 is about 866.9789868113.

The spelling of 651666978 in words is "six hundred fifty-one million, six hundred sixty-six thousand, nine hundred seventy-eight".