661571646 has 8 divisors (see below), whose sum is σ = 1323143304. Its totient is φ = 220523880.

The previous prime is 661571629. The next prime is 661571663. The reversal of 661571646 is 646175166.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (661571629) and next prime (661571663).

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

661571646 is an admirable number.

It is a super-2 number, since 2×661571646² = 875354085582298632, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 661571598 and 661571607.

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, 55130965 + ... + 55130976.

It is an arithmetic number, because the mean of its divisors is an integer number (165392913).

Almost surely, 2^661571646 is an apocalyptic number.

661571646 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661571646 is a wasteful number, since it uses less digits than its factorization.

661571646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110261946.

The product of its digits is 181440, while the sum is 42.

The square root of 661571646 is about 25721.0350880364. The cubic root of 661571646 is about 871.3493159105.

The spelling of 661571646 in words is "six hundred sixty-one million, five hundred seventy-one thousand, six hundred forty-six".