661782912 has 128 divisors (see below), whose sum is σ = 2021068800. Its totient is φ = 187944960.

The previous prime is 661782899. The next prime is 661782917. The reversal of 661782912 is 219287166.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661782917) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 512764 + ... + 514052.

It is an arithmetic number, because the mean of its divisors is an integer number (15789600).

Almost surely, 2^661782912 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 661782912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1010534400).

661782912 is an abundant number, since it is smaller than the sum of its proper divisors (1359285888).

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

661782912 is a wasteful number, since it uses less digits than its factorization.

661782912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1504 (or 1492 counting only the distinct ones).

The product of its digits is 72576, while the sum is 42.

The square root of 661782912 is about 25725.1416322632. The cubic root of 661782912 is about 871.4420581422.

The spelling of 661782912 in words is "six hundred sixty-one million, seven hundred eighty-two thousand, nine hundred twelve".