81691452826 has 8 divisors (see below), whose sum is σ = 129745248660. Its totient is φ = 38443036608.

The previous prime is 81691452757. The next prime is 81691452839. The reversal of 81691452826 is 62825419618.

It can be written as a sum of positive squares in 2 ways, for example, as 66874477201 + 14816975625 = 258601^2 + 121725^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1201344861 + ... + 1201344928.

Almost surely, 2^81691452826 is an apocalyptic number.

81691452826 is a deficient number, since it is larger than the sum of its proper divisors (48053795834).

81691452826 is a wasteful number, since it uses less digits than its factorization.

81691452826 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2402689808.

The product of its digits is 1658880, while the sum is 52.

The spelling of 81691452826 in words is "eighty-one billion, six hundred ninety-one million, four hundred fifty-two thousand, eight hundred twenty-six".