661421317 has 2 divisors, whose sum is σ = 661421318. Its totient is φ = 661421316.

The previous prime is 661421311. The next prime is 661421333. The reversal of 661421317 is 713124166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 471367521 + 190053796 = 21711^2 + 13786^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661421317 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661421311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330710658 + 330710659.

It is an arithmetic number, because the mean of its divisors is an integer number (330710659).

Almost surely, 2^661421317 is an apocalyptic number.

It is an amenable number.

661421317 is a deficient number, since it is larger than the sum of its proper divisors (1).

661421317 is an equidigital number, since it uses as much as digits as its factorization.

661421317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6048, while the sum is 31.

The square root of 661421317 is about 25718.1126251519. The cubic root of 661421317 is about 871.2833119763.

The spelling of 661421317 in words is "six hundred sixty-one million, four hundred twenty-one thousand, three hundred seventeen".