661148720 has 40 divisors (see below), whose sum is σ = 1551556944. Its totient is φ = 261984512.

The previous prime is 661148689. The next prime is 661148723. The reversal of 661148720 is 27841166.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (661148723) 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, 30059 + ... + 47178.

Almost surely, 2^661148720 is an apocalyptic number.

It is an amenable number.

661148720 is an abundant number, since it is smaller than the sum of its proper divisors (890408224).

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

661148720 is a wasteful number, since it uses less digits than its factorization.

661148720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77357 (or 77351 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 661148720 is about 25712.8123704895. The cubic root of 661148720 is about 871.1635991462.

Adding to 661148720 its reverse (27841166), we get a palindrome (688989886).

The spelling of 661148720 in words is "six hundred sixty-one million, one hundred forty-eight thousand, seven hundred twenty".