661309588 has 12 divisors (see below), whose sum is σ = 1225367892. Its totient is φ = 311204480.

The previous prime is 661309529. The next prime is 661309603. The reversal of 661309588 is 885903166.

It can be written as a sum of positive squares in 2 ways, for example, as 456762384 + 204547204 = 21372^2 + 14302^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4862503 + ... + 4862638.

It is an arithmetic number, because the mean of its divisors is an integer number (102113991).

Almost surely, 2^661309588 is an apocalyptic number.

661309588 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

661309588 is a deficient number, since it is larger than the sum of its proper divisors (564058304).

661309588 is a wasteful number, since it uses less digits than its factorization.

661309588 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9725162 (or 9725160 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 46.

The square root of 661309588 is about 25715.9403483520. The cubic root of 661309588 is about 871.2342494032.

It can be divided in two parts, 661 and 309588, that added together give a square (310249 = 557²).

The spelling of 661309588 in words is "six hundred sixty-one million, three hundred nine thousand, five hundred eighty-eight".