81418511 has 4 divisors (see below), whose sum is σ = 81438432. Its totient is φ = 81398592.

The previous prime is 81418507. The next prime is 81418529. The reversal of 81418511 is 11581418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11581418 = 2 ⋅5790709.

It is a cyclic number.

It is not a de Polignac number, because 81418511 - 2² = 81418507 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81418541) 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, 1346 + ... + 12831.

It is an arithmetic number, because the mean of its divisors is an integer number (20359608).

Almost surely, 2^81418511 is an apocalyptic number.

81418511 is a deficient number, since it is larger than the sum of its proper divisors (19921).

81418511 is a wasteful number, since it uses less digits than its factorization.

81418511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19920.

The product of its digits is 1280, while the sum is 29.

The square root of 81418511 is about 9023.2206556196. The cubic root of 81418511 is about 433.4187732251.

Adding to 81418511 its reverse (11581418), we get a palindrome (92999929).

The spelling of 81418511 in words is "eighty-one million, four hundred eighteen thousand, five hundred eleven".