691399 has 2 divisors, whose sum is σ = 691400. Its totient is φ = 691398.

The previous prime is 691381. The next prime is 691409. The reversal of 691399 is 993196.

691399 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 691399 - 2⁹ = 690887 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 (691309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345699 + 345700.

It is an arithmetic number, because the mean of its divisors is an integer number (345700).

2⁶⁹¹³⁹⁹ is an apocalyptic number.

691399 is a deficient number, since it is larger than the sum of its proper divisors (1).

691399 is an equidigital number, since it uses as much as digits as its factorization.

691399 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13122, while the sum is 37.

The square root of 691399 is about 831.5040589197. The cubic root of 691399 is about 88.4252403646.

The spelling of 691399 in words is "six hundred ninety-one thousand, three hundred ninety-nine".