661311806 has 8 divisors (see below), whose sum is σ = 992099664. Its totient is φ = 330611920.

The previous prime is 661311803. The next prime is 661311823. The reversal of 661311806 is 608113166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661311803) 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 3 ways as a sum of consecutive naturals, for example, 2066 + ... + 36426.

It is an arithmetic number, because the mean of its divisors is an integer number (124012458).

Almost surely, 2^661311806 is an apocalyptic number.

661311806 is a deficient number, since it is larger than the sum of its proper divisors (330787858).

661311806 is a wasteful number, since it uses less digits than its factorization.

661311806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43986.

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 661311806 is about 25715.9834733187. The cubic root of 661311806 is about 871.2352234278.

The spelling of 661311806 in words is "six hundred sixty-one million, three hundred eleven thousand, eight hundred six".