661586661 has 12 divisors (see below), whose sum is σ = 956690592. Its totient is φ = 440566056.

The previous prime is 661586659. The next prime is 661586687. The reversal of 661586661 is 166685166.

It is not a de Polignac number, because 661586661 - 2¹ = 661586659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661586621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32361 + ... + 48686.

It is an arithmetic number, because the mean of its divisors is an integer number (79724216).

Almost surely, 2^661586661 is an apocalyptic number.

It is an amenable number.

661586661 is a deficient number, since it is larger than the sum of its proper divisors (295103931).

661586661 is a wasteful number, since it uses less digits than its factorization.

661586661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81960 (or 81957 counting only the distinct ones).

The product of its digits is 311040, while the sum is 45.

The square root of 661586661 is about 25721.3269681018. The cubic root of 661586661 is about 871.3559078954.

The spelling of 661586661 in words is "six hundred sixty-one million, five hundred eighty-six thousand, six hundred sixty-one".