81034991 has 4 divisors (see below), whose sum is σ = 81579000. Its totient is φ = 80490984.

The previous prime is 81034979. The next prime is 81035011. The reversal of 81034991 is 19943018.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19943018 = 2 ⋅9971509.

It is a cyclic number.

It is not a de Polignac number, because 81034991 - 2¹⁴ = 81018607 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 (81034931) 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, 271781 + ... + 272078.

It is an arithmetic number, because the mean of its divisors is an integer number (20394750).

Almost surely, 2^81034991 is an apocalyptic number.

81034991 is a deficient number, since it is larger than the sum of its proper divisors (544009).

81034991 is a wasteful number, since it uses less digits than its factorization.

81034991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 544008.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 81034991 is about 9001.9437345498. The cubic root of 81034991 is about 432.7371655238.

The spelling of 81034991 in words is "eighty-one million, thirty-four thousand, nine hundred ninety-one".