661061661 has 32 divisors (see below), whose sum is σ = 1022461440. Its totient is φ = 376415424.

The previous prime is 661061593. The next prime is 661061663. The reversal of 661061661 is 166160166.

It is not a de Polignac number, because 661061661 - 2¹⁰ = 661060637 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661061663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21490 + ... + 42236.

It is an arithmetic number, because the mean of its divisors is an integer number (31951920).

Almost surely, 2^661061661 is an apocalyptic number.

It is an amenable number.

661061661 is a deficient number, since it is larger than the sum of its proper divisors (361399779).

661061661 is a wasteful number, since it uses less digits than its factorization.

661061661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20825.

The product of its (nonzero) digits is 7776, while the sum is 33.

The square root of 661061661 is about 25711.1194038688. The cubic root of 661061661 is about 871.1253596605.

The spelling of 661061661 in words is "six hundred sixty-one million, sixty-one thousand, six hundred sixty-one".