81138335 has 4 divisors (see below), whose sum is σ = 97366008. Its totient is φ = 64910664.

The previous prime is 81138313. The next prime is 81138347. The reversal of 81138335 is 53383118.

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 81138335 - 2⁶ = 81138271 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8113829 + ... + 8113838.

It is an arithmetic number, because the mean of its divisors is an integer number (24341502).

Almost surely, 2^81138335 is an apocalyptic number.

81138335 is a deficient number, since it is larger than the sum of its proper divisors (16227673).

81138335 is a wasteful number, since it uses less digits than its factorization.

81138335 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16227672.

The product of its digits is 8640, while the sum is 32.

The square root of 81138335 is about 9007.6819992715. The cubic root of 81138335 is about 432.9210440834.

The spelling of 81138335 in words is "eighty-one million, one hundred thirty-eight thousand, three hundred thirty-five".