81768406 has 4 divisors (see below), whose sum is σ = 122652612. Its totient is φ = 40884202.

The previous prime is 81768403. The next prime is 81768451. The reversal of 81768406 is 60486718.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 60486718 = 2 ⋅30243359.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81768403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20442100 + ... + 20442103.

It is an arithmetic number, because the mean of its divisors is an integer number (30663153).

Almost surely, 2^81768406 is an apocalyptic number.

81768406 is a deficient number, since it is larger than the sum of its proper divisors (40884206).

81768406 is a wasteful number, since it uses less digits than its factorization.

81768406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40884205.

The product of its (nonzero) digits is 64512, while the sum is 40.

The square root of 81768406 is about 9042.5884568524. The cubic root of 81768406 is about 434.0387564758.

The spelling of 81768406 in words is "eighty-one million, seven hundred sixty-eight thousand, four hundred six".