81015391 has 8 divisors (see below), whose sum is σ = 81723600. Its totient is φ = 80310720.

The previous prime is 81015383. The next prime is 81015409. The reversal of 81015391 is 19351018.

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 81015391 - 2³ = 81015383 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 (81015191) 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, 63720 + ... + 64978.

It is an arithmetic number, because the mean of its divisors is an integer number (10215450).

Almost surely, 2^81015391 is an apocalyptic number.

81015391 is a deficient number, since it is larger than the sum of its proper divisors (708209).

81015391 is a wasteful number, since it uses less digits than its factorization.

81015391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1769.

The product of its (nonzero) digits is 1080, while the sum is 28.

The square root of 81015391 is about 9000.8550149416. The cubic root of 81015391 is about 432.7022738791.

It can be divided in two parts, 81015 and 391, that added together give a triangular number (81406 = T₄₀₃).

The spelling of 81015391 in words is "eighty-one million, fifteen thousand, three hundred ninety-one".