661666742 has 8 divisors (see below), whose sum is σ = 1082727432. Its totient is φ = 300757600.

The previous prime is 661666739. The next prime is 661666751. The reversal of 661666742 is 247666166.

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

It is a junction number, because it is equal to n+sod(n) for n = 661666693 and 661666702.

It is a congruent number.

It is an unprimeable number.

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, 15037859 + ... + 15037902.

It is an arithmetic number, because the mean of its divisors is an integer number (135340929).

Almost surely, 2^661666742 is an apocalyptic number.

661666742 is a deficient number, since it is larger than the sum of its proper divisors (421060690).

661666742 is a wasteful number, since it uses less digits than its factorization.

661666742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30075774.

The product of its digits is 435456, while the sum is 44.

The square root of 661666742 is about 25722.8836252859. The cubic root of 661666742 is about 871.3910639031.

The spelling of 661666742 in words is "six hundred sixty-one million, six hundred sixty-six thousand, seven hundred forty-two".