634868921 has 2 divisors, whose sum is σ = 634868922. Its totient is φ = 634868920.

The previous prime is 634868881. The next prime is 634868929. The reversal of 634868921 is 129868436.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 604618921 + 30250000 = 24589^2 + 5500^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-634868921 is a prime.

It is not a weakly prime, because it can be changed into another prime (634868929) 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, 317434460 + 317434461.

It is an arithmetic number, because the mean of its divisors is an integer number (317434461).

Almost surely, 2^634868921 is an apocalyptic number.

It is an amenable number.

634868921 is a deficient number, since it is larger than the sum of its proper divisors (1).

634868921 is an equidigital number, since it uses as much as digits as its factorization.

634868921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 497664, while the sum is 47.

The square root of 634868921 is about 25196.6053467526. The cubic root of 634868921 is about 859.4646573584.

The spelling of 634868921 in words is "six hundred thirty-four million, eight hundred sixty-eight thousand, nine hundred twenty-one".