661309587 has 6 divisors (see below), whose sum is σ = 955224972. Its totient is φ = 440873052.

The previous prime is 661309529. The next prime is 661309603. The reversal of 661309587 is 785903166.

It is a happy number.

661309587 is a `hidden beast` number, since 6 + 61 + 3 + 0 + 9 + 587 = 666.

661309587 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661309587 - 2¹¹ = 661307539 is a prime.

It is a super-2 number, since 2×661309587² = 874660739716221138, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661309507) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36739413 + ... + 36739430.

It is an arithmetic number, because the mean of its divisors is an integer number (159204162).

Almost surely, 2^661309587 is an apocalyptic number.

661309587 is a deficient number, since it is larger than the sum of its proper divisors (293915385).

661309587 is a wasteful number, since it uses less digits than its factorization.

661309587 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73478849 (or 73478846 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 45.

The square root of 661309587 is about 25715.9403289088. The cubic root of 661309587 is about 871.2342489641.

The spelling of 661309587 in words is "six hundred sixty-one million, three hundred nine thousand, five hundred eighty-seven".