691388059 has 4 divisors (see below), whose sum is σ = 691440904. Its totient is φ = 691335216.

The previous prime is 691388057. The next prime is 691388063. The reversal of 691388059 is 950883196.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 691388059 - 2¹ = 691388057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (691388051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9319 + ... + 38335.

It is an arithmetic number, because the mean of its divisors is an integer number (172860226).

Almost surely, 2^691388059 is an apocalyptic number.

691388059 is a deficient number, since it is larger than the sum of its proper divisors (52845).

691388059 is a wasteful number, since it uses less digits than its factorization.

691388059 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52844.

The product of its (nonzero) digits is 466560, while the sum is 49.

The square root of 691388059 is about 26294.2590502185. The cubic root of 691388059 is about 884.2477393561.

The spelling of 691388059 in words is "six hundred ninety-one million, three hundred eighty-eight thousand, fifty-nine".