81106961919 has 4 divisors (see below), whose sum is σ = 108142615896. Its totient is φ = 54071307944.

The previous prime is 81106961893. The next prime is 81106961933. The reversal of 81106961919 is 91916960118.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 81106961919 - 2¹³ = 81106953727 is a prime.

It is a super-2 number, since 2×81106961919² (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 (81106963919) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13517826984 + ... + 13517826989.

It is an arithmetic number, because the mean of its divisors is an integer number (27035653974).

Almost surely, 2^81106961919 is an apocalyptic number.

81106961919 is a deficient number, since it is larger than the sum of its proper divisors (27035653977).

81106961919 is a wasteful number, since it uses less digits than its factorization.

81106961919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27035653976.

The product of its (nonzero) digits is 209952, while the sum is 51.

The spelling of 81106961919 in words is "eighty-one billion, one hundred six million, nine hundred sixty-one thousand, nine hundred nineteen".