661579776 has 288 divisors, whose sum is σ = 2253756960. Its totient is φ = 184320000.

The previous prime is 661579771. The next prime is 661579799. The reversal of 661579776 is 677975166.

It is a happy number.

661579776 is a `hidden beast` number, since 6 + 61 + 579 + 7 + 7 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

Its product of digits (3333960) is a multiple of the sum of its prime divisors (280).

It is not an unprimeable number, because it can be changed into a prime (661579771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2635651 + ... + 2635901.

It is an arithmetic number, because the mean of its divisors is an integer number (7825545).

Almost surely, 2^661579776 is an apocalyptic number.

661579776 is a gapful number since it is divisible by the number (66) 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 661579776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1126878480).

661579776 is an abundant number, since it is smaller than the sum of its proper divisors (1592177184).

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

661579776 is a wasteful number, since it uses less digits than its factorization.

661579776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 303 (or 280 counting only the distinct ones).

The product of its digits is 3333960, while the sum is 54.

The square root of 661579776 is about 25721.1931294021. The cubic root of 661579776 is about 871.3528852094.

The spelling of 661579776 in words is "six hundred sixty-one million, five hundred seventy-nine thousand, seven hundred seventy-six".