661145320 has 64 divisors (see below), whose sum is σ = 1653488640. Its totient is φ = 235872000.

The previous prime is 661145297. The next prime is 661145357. The reversal of 661145320 is 23541166.

It is a super-2 number, since 2×661145320² = 874226268315804800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9145 + ... + 37495.

It is an arithmetic number, because the mean of its divisors is an integer number (25835760).

Almost surely, 2^661145320 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 661145320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (826744320).

661145320 is an abundant number, since it is smaller than the sum of its proper divisors (992343320).

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

661145320 is a wasteful number, since it uses less digits than its factorization.

661145320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28426 (or 28422 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 661145320 is about 25712.7462555053. The cubic root of 661145320 is about 871.1621058052.

Adding to 661145320 its reverse (23541166), we get a palindrome (684686486).

The spelling of 661145320 in words is "six hundred sixty-one million, one hundred forty-five thousand, three hundred twenty".