660721620 has 48 divisors (see below), whose sum is σ = 1992332160. Its totient is φ = 162638976.

The previous prime is 660721603. The next prime is 660721651. The reversal of 660721620 is 26127066.

It is a super-3 number, since 3×660721620³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

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 15 ways as a sum of consecutive naturals, for example, 422760 + ... + 424319.

It is an arithmetic number, because the mean of its divisors is an integer number (41506920).

Almost surely, 2^660721620 is an apocalyptic number.

660721620 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

660721620 is an abundant number, since it is smaller than the sum of its proper divisors (1331610540).

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

660721620 is a wasteful number, since it uses less digits than its factorization.

660721620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 847104 (or 847102 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 30.

The square root of 660721620 is about 25704.5058306905. The cubic root of 660721620 is about 870.9759690864.

Adding to 660721620 its reverse (26127066), we get a palindrome (686848686).

The spelling of 660721620 in words is "six hundred sixty million, seven hundred twenty-one thousand, six hundred twenty".