661129776 has 100 divisors (see below), whose sum is σ = 2014287000. Its totient is φ = 208770048.

The previous prime is 661129769. The next prime is 661129783. The reversal of 661129776 is 677921166.

It is a happy number.

661129776 is a `hidden beast` number, since 6 + 611 + 29 + 7 + 7 + 6 = 666.

It is an interprime number because it is at equal distance from previous prime (661129769) and next prime (661129783).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 11200 + ... + 38048.

It is an arithmetic number, because the mean of its divisors is an integer number (20142870).

Almost surely, 2^661129776 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661129776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1007143500).

661129776 is an abundant number, since it is smaller than the sum of its proper divisors (1353157224).

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

661129776 is a wasteful number, since it uses less digits than its factorization.

661129776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26888 (or 26873 counting only the distinct ones).

The product of its digits is 190512, while the sum is 45.

The square root of 661129776 is about 25712.4439911884. The cubic root of 661129776 is about 871.1552785367.

The spelling of 661129776 in words is "six hundred sixty-one million, one hundred twenty-nine thousand, seven hundred seventy-six".