694189021 has 2 divisors, whose sum is σ = 694189022. Its totient is φ = 694189020.

The previous prime is 694189007. The next prime is 694189049. The reversal of 694189021 is 120981496.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 369792900 + 324396121 = 19230^2 + 18011^2 .

It is a cyclic number.

It is not a de Polignac number, because 694189021 - 2⁷ = 694188893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (694189051) 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, 347094510 + 347094511.

It is an arithmetic number, because the mean of its divisors is an integer number (347094511).

Almost surely, 2^694189021 is an apocalyptic number.

It is an amenable number.

694189021 is a deficient number, since it is larger than the sum of its proper divisors (1).

694189021 is an equidigital number, since it uses as much as digits as its factorization.

694189021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 694189021 is about 26347.4670699102. The cubic root of 694189021 is about 885.4402231735.

The spelling of 694189021 in words is "six hundred ninety-four million, one hundred eighty-nine thousand, twenty-one".