81697621811 has 8 divisors (see below), whose sum is σ = 88158378000. Its totient is φ = 75262054752.

The previous prime is 81697621801. The next prime is 81697621909. The reversal of 81697621811 is 11812679618.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81697621811 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 81697621811.

It is not an unprimeable number, because it can be changed into a prime (81697621801) 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, 6290540 + ... + 6303513.

It is an arithmetic number, because the mean of its divisors is an integer number (11019797250).

Almost surely, 2^81697621811 is an apocalyptic number.

81697621811 is a deficient number, since it is larger than the sum of its proper divisors (6460756189).

81697621811 is a wasteful number, since it uses less digits than its factorization.

81697621811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12594565.

The product of its digits is 290304, while the sum is 50.

The spelling of 81697621811 in words is "eighty-one billion, six hundred ninety-seven million, six hundred twenty-one thousand, eight hundred eleven".