661309884 has 36 divisors (see below), whose sum is σ = 1672430760. Its totient is φ = 220332960.

The previous prime is 661309879. The next prime is 661309889. The reversal of 661309884 is 488903166.

It is an interprime number because it is at equal distance from previous prime (661309879) and next prime (661309889).

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661309889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 133614 + ... + 138474.

It is an arithmetic number, because the mean of its divisors is an integer number (46456410).

Almost surely, 2^661309884 is an apocalyptic number.

It is an amenable number.

661309884 is an abundant number, since it is smaller than the sum of its proper divisors (1011120876).

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

661309884 is a wasteful number, since it uses less digits than its factorization.

661309884 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8650 (or 8645 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 45.

The square root of 661309884 is about 25715.9461035366. The cubic root of 661309884 is about 871.2343793904.

The spelling of 661309884 in words is "six hundred sixty-one million, three hundred nine thousand, eight hundred eighty-four".