691573 has 2 divisors, whose sum is σ = 691574. Its totient is φ = 691572.

The previous prime is 691553. The next prime is 691583. The reversal of 691573 is 375196.

691573 is nontrivially palindromic in base 15.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 439569 + 252004 = 663^2 + 502^2 .

It is a cyclic number.

It is not a de Polignac number, because 691573 - 2¹³ = 683381 is a prime.

691573 is an undulating number in base 15.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691553) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345786 + 345787.

It is an arithmetic number, because the mean of its divisors is an integer number (345787).

2⁶⁹¹⁵⁷³ is an apocalyptic number.

It is an amenable number.

691573 is a deficient number, since it is larger than the sum of its proper divisors (1).

691573 is an equidigital number, since it uses as much as digits as its factorization.

691573 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5670, while the sum is 31.

The square root of 691573 is about 831.6086820134. The cubic root of 691573 is about 88.4326575489.

The spelling of 691573 in words is "six hundred ninety-one thousand, five hundred seventy-three".