81406439 has 4 divisors (see below), whose sum is σ = 83299656. Its totient is φ = 79513224.

The previous prime is 81406417. The next prime is 81406441. The reversal of 81406439 is 93460418.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81406439 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81406399 and 81406408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81406459) 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, 946544 + ... + 946629.

It is an arithmetic number, because the mean of its divisors is an integer number (20824914).

Almost surely, 2^81406439 is an apocalyptic number.

81406439 is a deficient number, since it is larger than the sum of its proper divisors (1893217).

81406439 is a wasteful number, since it uses less digits than its factorization.

81406439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1893216.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 81406439 is about 9022.5516900708. The cubic root of 81406439 is about 433.3973510285.

It can be divided in two parts, 814064 and 39, that multiplied together give a triangular number (31748496 = T₇₉₆₈).

The spelling of 81406439 in words is "eighty-one million, four hundred six thousand, four hundred thirty-nine".