661421333 has 2 divisors, whose sum is σ = 661421334. Its totient is φ = 661421332.

The previous prime is 661421317. The next prime is 661421377. The reversal of 661421333 is 333124166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 629859409 + 31561924 = 25097^2 + 5618^2 .

It is a cyclic number.

It is not a de Polignac number, because 661421333 - 2⁴ = 661421317 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 661421296 and 661421305.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661421633) by changing a digit.

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, 330710666 + 330710667.

It is an arithmetic number, because the mean of its divisors is an integer number (330710667).

Almost surely, 2^661421333 is an apocalyptic number.

It is an amenable number.

661421333 is a deficient number, since it is larger than the sum of its proper divisors (1).

661421333 is an equidigital number, since it uses as much as digits as its factorization.

661421333 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 29.

The square root of 661421333 is about 25718.1129362168. The cubic root of 661421333 is about 871.2833190018.

Adding to 661421333 its reverse (333124166), we get a palindrome (994545499).

The spelling of 661421333 in words is "six hundred sixty-one million, four hundred twenty-one thousand, three hundred thirty-three".