691276139 has 4 divisors (see below), whose sum is σ = 694376256. Its totient is φ = 688176024.

The previous prime is 691276129. The next prime is 691276163. The reversal of 691276139 is 931672196.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 691276139 - 2⁴ = 691276123 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 691276139.

It is not an unprimeable number, because it can be changed into a prime (691276129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1549724 + ... + 1550169.

It is an arithmetic number, because the mean of its divisors is an integer number (173594064).

Almost surely, 2^691276139 is an apocalyptic number.

691276139 is a deficient number, since it is larger than the sum of its proper divisors (3100117).

691276139 is a wasteful number, since it uses less digits than its factorization.

691276139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3100116.

The product of its digits is 122472, while the sum is 44.

The square root of 691276139 is about 26292.1307428668. The cubic root of 691276139 is about 884.2000235829.

The spelling of 691276139 in words is "six hundred ninety-one million, two hundred seventy-six thousand, one hundred thirty-nine".