655721020 has 12 divisors (see below), whose sum is σ = 1377014184. Its totient is φ = 262288400.

The previous prime is 655720981. The next prime is 655721041. The reversal of 655721020 is 20127556.

It is a self number, because there is not a number n which added to its sum of digits gives 655721020.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16393006 + ... + 16393045.

It is an arithmetic number, because the mean of its divisors is an integer number (114751182).

Almost surely, 2^655721020 is an apocalyptic number.

It is an amenable number.

655721020 is an abundant number, since it is smaller than the sum of its proper divisors (721293164).

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

655721020 is a wasteful number, since it uses less digits than its factorization.

655721020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32786060 (or 32786058 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 28.

The square root of 655721020 is about 25607.0502010677. The cubic root of 655721020 is about 868.7731065745.

Adding to 655721020 its reverse (20127556), we get a palindrome (675848576).

The spelling of 655721020 in words is "six hundred fifty-five million, seven hundred twenty-one thousand, twenty".