81513313 has 6 divisors (see below), whose sum is σ = 94821666. Its totient is φ = 69868512.

The previous prime is 81513259. The next prime is 81513319. The reversal of 81513313 is 31331518.

It can be written as a sum of positive squares in only one way, i.e., 55472704 + 26040609 = 7448^2 + 5103^2 .

It is not a de Polignac number, because 81513313 - 2¹⁷ = 81382241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81513319) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 831720 + ... + 831817.

It is an arithmetic number, because the mean of its divisors is an integer number (15803611).

Almost surely, 2^81513313 is an apocalyptic number.

It is an amenable number.

81513313 is a deficient number, since it is larger than the sum of its proper divisors (13308353).

81513313 is a wasteful number, since it uses less digits than its factorization.

81513313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1663551 (or 1663544 counting only the distinct ones).

The product of its digits is 1080, while the sum is 25.

The square root of 81513313 is about 9028.4723514003. The cubic root of 81513313 is about 433.5869292076.

The spelling of 81513313 in words is "eighty-one million, five hundred thirteen thousand, three hundred thirteen".