661010688 has 216 divisors, whose sum is σ = 2126025720. Its totient is φ = 196116480.

The previous prime is 661010687. The next prime is 661010719. The reversal of 661010688 is 886010166.

It can be written as a sum of positive squares in 4 ways, for example, as 16257024 + 644753664 = 4032^2 + 25392^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661010681) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 868228 + ... + 868988.

Almost surely, 2^661010688 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 661010688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1063012860).

661010688 is an abundant number, since it is smaller than the sum of its proper divisors (1465015032).

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

661010688 is a wasteful number, since it uses less digits than its factorization.

661010688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 825 (or 808 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 661010688 is about 25710.1281210343. The cubic root of 661010688 is about 871.1029689029.

The spelling of 661010688 in words is "six hundred sixty-one million, ten thousand, six hundred eighty-eight".