655612021 has 4 divisors (see below), whose sum is σ = 694177452. Its totient is φ = 617046592.

The previous prime is 655612007. The next prime is 655612057. The reversal of 655612021 is 120216556.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 281769796 + 373842225 = 16786^2 + 19335^2 .

It is a cyclic number.

It is not a de Polignac number, because 655612021 - 2⁵ = 655611989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (655612121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19282690 + ... + 19282723.

It is an arithmetic number, because the mean of its divisors is an integer number (173544363).

Almost surely, 2^655612021 is an apocalyptic number.

It is an amenable number.

655612021 is a deficient number, since it is larger than the sum of its proper divisors (38565431).

655612021 is a wasteful number, since it uses less digits than its factorization.

655612021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38565430.

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 655612021 is about 25604.9218120267. The cubic root of 655612021 is about 868.7249658538.

Adding to 655612021 its reverse (120216556), we get a palindrome (775828577).

The spelling of 655612021 in words is "six hundred fifty-five million, six hundred twelve thousand, twenty-one".