691071406509 has 16 divisors (see below), whose sum is σ = 1026581898240. Its totient is φ = 409919853360.

The previous prime is 691071406499. The next prime is 691071406547. The reversal of 691071406509 is 905604170196.

It is a happy number.

It is not a de Polignac number, because 691071406509 - 2⁵ = 691071406477 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691071404509) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 222780979 + ... + 222784080.

It is an arithmetic number, because the mean of its divisors is an integer number (64161368640).

Almost surely, 2^691071406509 is an apocalyptic number.

It is an amenable number.

691071406509 is a deficient number, since it is larger than the sum of its proper divisors (335510491731).

691071406509 is a wasteful number, since it uses less digits than its factorization.

691071406509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 445565120.

The product of its (nonzero) digits is 408240, while the sum is 48.

The spelling of 691071406509 in words is "six hundred ninety-one billion, seventy-one million, four hundred six thousand, five hundred nine".