691129 has 2 divisors, whose sum is σ = 691130. Its totient is φ = 691128.

The previous prime is 691121. The next prime is 691147. The reversal of 691129 is 921196.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 570025 + 121104 = 755^2 + 348^2 .

It is a cyclic number.

It is not a de Polignac number, because 691129 - 2³ = 691121 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 691097 and 691106.

It is not a weakly prime, because it can be changed into another prime (691121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345564 + 345565.

It is an arithmetic number, because the mean of its divisors is an integer number (345565).

2⁶⁹¹¹²⁹ is an apocalyptic number.

It is an amenable number.

691129 is a deficient number, since it is larger than the sum of its proper divisors (1).

691129 is an equidigital number, since it uses as much as digits as its factorization.

691129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 972, while the sum is 28.

The square root of 691129 is about 831.3416866728. The cubic root of 691129 is about 88.4137284767.

It can be divided in two parts, 691 and 129, that added together give a triangular number (820 = T₄₀).

The spelling of 691129 in words is "six hundred ninety-one thousand, one hundred twenty-nine".