661497440 has 48 divisors (see below), whose sum is σ = 1568966112. Its totient is φ = 263553024.

The previous prime is 661497427. The next prime is 661497443. The reversal of 661497440 is 44794166.

661497440 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661497443) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33077 + ... + 49163.

It is an arithmetic number, because the mean of its divisors is an integer number (32686794).

Almost surely, 2^661497440 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 661497440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (784483056).

661497440 is an abundant number, since it is smaller than the sum of its proper divisors (907468672).

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

661497440 is a wasteful number, since it uses less digits than its factorization.

661497440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16359 (or 16351 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 41.

The square root of 661497440 is about 25719.5925317646. The cubic root of 661497440 is about 871.3167360353.

The spelling of 661497440 in words is "six hundred sixty-one million, four hundred ninety-seven thousand, four hundred forty".