691157543 has 2 divisors, whose sum is σ = 691157544. Its totient is φ = 691157542.

The previous prime is 691157507. The next prime is 691157563. The reversal of 691157543 is 345751196.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 691157543 - 2⁶ = 691157479 is a prime.

It is equal to p_35818781 and since 691157543 and 35818781 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 691157543.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691157563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345578771 + 345578772.

It is an arithmetic number, because the mean of its divisors is an integer number (345578772).

Almost surely, 2^691157543 is an apocalyptic number.

691157543 is a deficient number, since it is larger than the sum of its proper divisors (1).

691157543 is an equidigital number, since it uses as much as digits as its factorization.

691157543 is an evil number, because the sum of its binary digits is even.

The product of its digits is 113400, while the sum is 41.

The square root of 691157543 is about 26289.8752944931. The cubic root of 691157543 is about 884.1494559552.

The spelling of 691157543 in words is "six hundred ninety-one million, one hundred fifty-seven thousand, five hundred forty-three".