661501664 has 12 divisors (see below), whose sum is σ = 1302331464. Its totient is φ = 330750816.

The previous prime is 661501627. The next prime is 661501693. The reversal of 661501664 is 466105166.

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 as a sum of consecutive naturals, namely, 10335932 + ... + 10335995.

It is an arithmetic number, because the mean of its divisors is an integer number (108527622).

Almost surely, 2^661501664 is an apocalyptic number.

It is an amenable number.

661501664 is a deficient number, since it is larger than the sum of its proper divisors (640829800).

661501664 is a wasteful number, since it uses less digits than its factorization.

661501664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20671937 (or 20671929 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 661501664 is about 25719.6746480199. The cubic root of 661501664 is about 871.3185906325.

The spelling of 661501664 in words is "six hundred sixty-one million, five hundred one thousand, six hundred sixty-four".