81211467381 has 16 divisors (see below), whose sum is σ = 118685618688. Its totient is φ = 48985801200.

The previous prime is 81211467319. The next prime is 81211467409. The reversal of 81211467381 is 18376411218.

It is not a de Polignac number, because 81211467381 - 2³⁵ = 46851729013 is a prime.

It is a super-2 number, since 2×81211467381² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81211467301) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5824681 + ... + 5838606.

It is an arithmetic number, because the mean of its divisors is an integer number (7417851168).

Almost surely, 2^81211467381 is an apocalyptic number.

It is an amenable number.

81211467381 is a deficient number, since it is larger than the sum of its proper divisors (37474151307).

81211467381 is a wasteful number, since it uses less digits than its factorization.

81211467381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11663512.

The product of its digits is 64512, while the sum is 42.

Adding to 81211467381 its reverse (18376411218), we get a palindrome (99587878599).

The spelling of 81211467381 in words is "eighty-one billion, two hundred eleven million, four hundred sixty-seven thousand, three hundred eighty-one".