81019309 has 4 divisors (see below), whose sum is σ = 92593504. Its totient is φ = 69445116.

The previous prime is 81019291. The next prime is 81019333. The reversal of 81019309 is 90391018.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81019309 - 2¹⁵ = 80986541 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 (81019339) 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, 5787087 + ... + 5787100.

It is an arithmetic number, because the mean of its divisors is an integer number (23148376).

Almost surely, 2^81019309 is an apocalyptic number.

It is an amenable number.

81019309 is a deficient number, since it is larger than the sum of its proper divisors (11574195).

81019309 is a wasteful number, since it uses less digits than its factorization.

81019309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11574194.

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 81019309 is about 9001.0726583002. The cubic root of 81019309 is about 432.7092490976.

The spelling of 81019309 in words is "eighty-one million, nineteen thousand, three hundred nine".