81951011 has 4 divisors (see below), whose sum is σ = 84594624. Its totient is φ = 79307400.

The previous prime is 81950959. The next prime is 81951061. The reversal of 81951011 is 11015918.

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

It is a cyclic number.

It is not a de Polignac number, because 81951011 - 2¹⁴ = 81934627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81951061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1321760 + ... + 1321821.

It is an arithmetic number, because the mean of its divisors is an integer number (21148656).

Almost surely, 2^81951011 is an apocalyptic number.

81951011 is a deficient number, since it is larger than the sum of its proper divisors (2643613).

81951011 is a wasteful number, since it uses less digits than its factorization.

81951011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2643612.

The product of its (nonzero) digits is 360, while the sum is 26.

The square root of 81951011 is about 9052.6797689966. The cubic root of 81951011 is about 434.3616143487.

Adding to 81951011 its reverse (11015918), we get a palindrome (92966929).

The spelling of 81951011 in words is "eighty-one million, nine hundred fifty-one thousand, eleven".