81451913 has 8 divisors (see below), whose sum is σ = 86627232. Its totient is φ = 76319296.

The previous prime is 81451883. The next prime is 81451921. The reversal of 81451913 is 31915418.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81451913 - 2¹⁸ = 81189769 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81451913.

It is not an unprimeable number, because it can be changed into a prime (81451943) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6695 + ... + 14412.

It is an arithmetic number, because the mean of its divisors is an integer number (10828404).

Almost surely, 2^81451913 is an apocalyptic number.

It is an amenable number.

81451913 is a deficient number, since it is larger than the sum of its proper divisors (5175319).

81451913 is a wasteful number, since it uses less digits than its factorization.

81451913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21351.

The product of its digits is 4320, while the sum is 32.

The square root of 81451913 is about 9025.0713570586. The cubic root of 81451913 is about 433.4780352381.

The spelling of 81451913 in words is "eighty-one million, four hundred fifty-one thousand, nine hundred thirteen".