81909683407 has 4 divisors (see below), whose sum is σ = 86727900096. Its totient is φ = 77091466720.

The previous prime is 81909683393. The next prime is 81909683417. The reversal of 81909683407 is 70438690918.

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

It is not a de Polignac number, because 81909683407 - 2¹⁵ = 81909650639 is a prime.

It is a super-2 number, since 2×81909683407² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81909683417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2409108319 + ... + 2409108352.

It is an arithmetic number, because the mean of its divisors is an integer number (21681975024).

Almost surely, 2^81909683407 is an apocalyptic number.

81909683407 is a deficient number, since it is larger than the sum of its proper divisors (4818216689).

81909683407 is a wasteful number, since it uses less digits than its factorization.

81909683407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4818216688.

The product of its (nonzero) digits is 2612736, while the sum is 55.

The spelling of 81909683407 in words is "eighty-one billion, nine hundred nine million, six hundred eighty-three thousand, four hundred seven".