661076640 has 432 divisors, whose sum is σ = 2729274912. Its totient is φ = 150667776.

The previous prime is 661076639. The next prime is 661076677. The reversal of 661076640 is 46670166.

661076640 is a `hidden beast` number, since 6 + 6 + 1 + 0 + 7 + 6 + 640 = 666.

661076640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (432).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 661076595 and 661076604.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1904947 + ... + 1905293.

It is an arithmetic number, because the mean of its divisors is an integer number (6317766).

Almost surely, 2^661076640 is an apocalyptic number.

661076640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661076640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1364637456).

661076640 is an abundant number, since it is smaller than the sum of its proper divisors (2068198272).

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

661076640 is a wasteful number, since it uses less digits than its factorization.

661076640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391 (or 364 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The square root of 661076640 is about 25711.4106964204. The cubic root of 661076640 is about 871.1319392223.

The spelling of 661076640 in words is "six hundred sixty-one million, seventy-six thousand, six hundred forty".