655612121 has 2 divisors, whose sum is σ = 655612122. Its totient is φ = 655612120.

The previous prime is 655612063. The next prime is 655612141. The reversal of 655612121 is 121216556.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 575760025 + 79852096 = 23995^2 + 8936^2 .

It is a cyclic number.

It is not a de Polignac number, because 655612121 - 2⁶ = 655612057 is a prime.

It is not a weakly prime, because it can be changed into another prime (655612141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 327806060 + 327806061.

It is an arithmetic number, because the mean of its divisors is an integer number (327806061).

Almost surely, 2^655612121 is an apocalyptic number.

It is an amenable number.

655612121 is a deficient number, since it is larger than the sum of its proper divisors (1).

655612121 is an equidigital number, since it uses as much as digits as its factorization.

655612121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3600, while the sum is 29.

The square root of 655612121 is about 25604.9237647762. The cubic root of 655612121 is about 868.7250100225.

Adding to 655612121 its reverse (121216556), we get a palindrome (776828677).

The spelling of 655612121 in words is "six hundred fifty-five million, six hundred twelve thousand, one hundred twenty-one".