690726389 has 2 divisors, whose sum is σ = 690726390. Its totient is φ = 690726388.

The previous prime is 690726347. The next prime is 690726401. The reversal of 690726389 is 983627096.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 460445764 + 230280625 = 21458^2 + 15175^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-690726389 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (690726889) 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, 345363194 + 345363195.

It is an arithmetic number, because the mean of its divisors is an integer number (345363195).

Almost surely, 2^690726389 is an apocalyptic number.

It is an amenable number.

690726389 is a deficient number, since it is larger than the sum of its proper divisors (1).

690726389 is an equidigital number, since it uses as much as digits as its factorization.

690726389 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 979776, while the sum is 50.

The square root of 690726389 is about 26281.6740144154. The cubic root of 690726389 is about 883.9655693373.

The spelling of 690726389 in words is "six hundred ninety million, seven hundred twenty-six thousand, three hundred eighty-nine".