661116566 has 16 divisors (see below), whose sum is σ = 1086045840. Its totient is φ = 299335680.

The previous prime is 661116563. The next prime is 661116569. The reversal of 661116566 is 665611166.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (661116563) and next prime (661116569).

It is a super-2 number, since 2×661116566² = 874150227679264712, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661116563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52811 + ... + 64118.

It is an arithmetic number, because the mean of its divisors is an integer number (67877865).

Almost surely, 2^661116566 is an apocalyptic number.

661116566 is a deficient number, since it is larger than the sum of its proper divisors (424929274).

661116566 is a wasteful number, since it uses less digits than its factorization.

661116566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117199.

The product of its digits is 38880, while the sum is 38.

The square root of 661116566 is about 25712.1871103957. The cubic root of 661116566 is about 871.1494763285.

The spelling of 661116566 in words is "six hundred sixty-one million, one hundred sixteen thousand, five hundred sixty-six".