661303440 has 400 divisors, whose sum is σ = 2679114240. Its totient is φ = 148055040.

The previous prime is 661303427. The next prime is 661303441. The reversal of 661303440 is 44303166.

661303440 is a `hidden beast` number, since 6 + 613 + 0 + 3 + 4 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661303441) 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 79 ways as a sum of consecutive naturals, for example, 2766841 + ... + 2767079.

Almost surely, 2^661303440 is an apocalyptic number.

661303440 is a gapful number since it is divisible by the number (60) 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 661303440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1339557120).

661303440 is an abundant number, since it is smaller than the sum of its proper divisors (2017810800).

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

661303440 is a wasteful number, since it uses less digits than its factorization.

661303440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332 (or 317 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 27.

The square root of 661303440 is about 25715.8208113216. The cubic root of 661303440 is about 871.2315495257.

The spelling of 661303440 in words is "six hundred sixty-one million, three hundred three thousand, four hundred forty".