661064568 has 64 divisors (see below), whose sum is σ = 1742601600. Its totient is φ = 208402560.

The previous prime is 661064563. The next prime is 661064623. The reversal of 661064568 is 865460166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661064563) 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, 442030 + ... + 443522.

It is an arithmetic number, because the mean of its divisors is an integer number (27228150).

Almost surely, 2^661064568 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 661064568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (871300800).

661064568 is an abundant number, since it is smaller than the sum of its proper divisors (1081537032).

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

661064568 is a wasteful number, since it uses less digits than its factorization.

661064568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2492 (or 2488 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 42.

The square root of 661064568 is about 25711.1759357677. The cubic root of 661064568 is about 871.1266365750.

The spelling of 661064568 in words is "six hundred sixty-one million, sixty-four thousand, five hundred sixty-eight".