81403913 has 4 divisors (see below), whose sum is σ = 81472020. Its totient is φ = 81335808.

The previous prime is 81403867. The next prime is 81403921. The reversal of 81403913 is 31930418.

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

It can be written as a sum of positive squares in 2 ways, for example, as 30880249 + 50523664 = 5557^2 + 7108^2 .

It is a cyclic number.

It is not a de Polignac number, because 81403913 - 2⁶ = 81403849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81403943) 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, 32228 + ... + 34661.

It is an arithmetic number, because the mean of its divisors is an integer number (20368005).

Almost surely, 2^81403913 is an apocalyptic number.

It is an amenable number.

81403913 is a deficient number, since it is larger than the sum of its proper divisors (68107).

81403913 is a wasteful number, since it uses less digits than its factorization.

81403913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68106.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 81403913 is about 9022.4117064120. The cubic root of 81403913 is about 433.3928682831.

The spelling of 81403913 in words is "eighty-one million, four hundred three thousand, nine hundred thirteen".