661099776 has 72 divisors (see below), whose sum is σ = 1820222880. Its totient is φ = 212760576.

The previous prime is 661099771. The next prime is 661099783. The reversal of 661099776 is 677990166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661099771) 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 7 ways as a sum of consecutive naturals, for example, 7431 + ... + 37113.

Almost surely, 2^661099776 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 661099776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (910111440).

661099776 is an abundant number, since it is smaller than the sum of its proper divisors (1159123104).

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

661099776 is a wasteful number, since it uses less digits than its factorization.

661099776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29731 (or 29717 counting only the distinct ones).

The product of its (nonzero) digits is 857304, while the sum is 51.

The square root of 661099776 is about 25711.8606094542. The cubic root of 661099776 is about 871.1421015707.

The spelling of 661099776 in words is "six hundred sixty-one million, ninety-nine thousand, seven hundred seventy-six".