691845057 has 14 divisors (see below), whose sum is σ = 1037294162. Its totient is φ = 461229552.

The previous prime is 691845047. The next prime is 691845101. The reversal of 691845057 is 750548196.

691845057 is a `hidden beast` number, since 69 + 1 + 84 + 505 + 7 = 666.

It can be written as a sum of positive squares in only one way, i.e., 690165441 + 1679616 = 26271^2 + 1296^2 .

It is not a de Polignac number, because 691845057 - 2²⁰ = 690796481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (691845047) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 473788 + ... + 475245.

Almost surely, 2^691845057 is an apocalyptic number.

It is an amenable number.

691845057 is a deficient number, since it is larger than the sum of its proper divisors (345449105).

691845057 is an frugal number, since it uses more digits than its factorization.

691845057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 949051 (or 949036 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The square root of 691845057 is about 26302.9476865237. The cubic root of 691845057 is about 884.4425216452.

The spelling of 691845057 in words is "six hundred ninety-one million, eight hundred forty-five thousand, fifty-seven".