81993739967 has 8 divisors (see below), whose sum is σ = 82433878800. Its totient is φ = 81554774400.

The previous prime is 81993739963. The next prime is 81993739969. The reversal of 81993739967 is 76993739918.

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

It is a cyclic number.

It is not a de Polignac number, because 81993739967 - 2² = 81993739963 is a prime.

It is a super-2 number, since 2×81993739967² (a number of 23 digits) contains 22 as substring.

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 81993739967.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81993739963) 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, 152993 + ... + 432890.

It is an arithmetic number, because the mean of its divisors is an integer number (10304234850).

Almost surely, 2^81993739967 is an apocalyptic number.

81993739967 is a deficient number, since it is larger than the sum of its proper divisors (440138833).

81993739967 is a wasteful number, since it uses less digits than its factorization.

81993739967 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 586633.

The product of its digits is 138883248, while the sum is 71.

The spelling of 81993739967 in words is "eighty-one billion, nine hundred ninety-three million, seven hundred thirty-nine thousand, nine hundred sixty-seven".