687721429 has 2 divisors, whose sum is σ = 687721430. Its totient is φ = 687721428.

The previous prime is 687721427. The next prime is 687721487. The reversal of 687721429 is 924127786.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 368563204 + 319158225 = 19198^2 + 17865^2 .

It is a cyclic number.

It is not a de Polignac number, because 687721429 - 2¹ = 687721427 is a prime.

Together with 687721427, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687721427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343860714 + 343860715.

It is an arithmetic number, because the mean of its divisors is an integer number (343860715).

Almost surely, 2^687721429 is an apocalyptic number.

It is an amenable number.

687721429 is a deficient number, since it is larger than the sum of its proper divisors (1).

687721429 is an equidigital number, since it uses as much as digits as its factorization.

687721429 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 338688, while the sum is 46.

The square root of 687721429 is about 26224.4433496690. The cubic root of 687721429 is about 882.6818277820.

The spelling of 687721429 in words is "six hundred eighty-seven million, seven hundred twenty-one thousand, four hundred twenty-nine".