81861690567 has 8 divisors (see below), whose sum is σ = 109167831040. Its totient is φ = 54565005240.

The previous prime is 81861690553. The next prime is 81861690569. The reversal of 81861690567 is 76509616818.

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

It is not a de Polignac number, because 81861690567 - 2⁸ = 81861690311 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81861690569) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2343559 + ... + 2378232.

It is an arithmetic number, because the mean of its divisors is an integer number (13645978880).

Almost surely, 2^81861690567 is an apocalyptic number.

81861690567 is a deficient number, since it is larger than the sum of its proper divisors (27306140473).

81861690567 is a wasteful number, since it uses less digits than its factorization.

81861690567 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4727573.

The product of its (nonzero) digits is 4354560, while the sum is 57.

The spelling of 81861690567 in words is "eighty-one billion, eight hundred sixty-one million, six hundred ninety thousand, five hundred sixty-seven".