81011806 has 4 divisors (see below), whose sum is σ = 121517712. Its totient is φ = 40505902.

The previous prime is 81011803. The next prime is 81011809. The reversal of 81011806 is 60811018.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (81011803) and next prime (81011809).

It is a super-2 number, since 2×81011806² = 13125825422763272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81011803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20252950 + ... + 20252953.

It is an arithmetic number, because the mean of its divisors is an integer number (30379428).

Almost surely, 2^81011806 is an apocalyptic number.

81011806 is a deficient number, since it is larger than the sum of its proper divisors (40505906).

81011806 is a wasteful number, since it uses less digits than its factorization.

81011806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40505905.

The product of its (nonzero) digits is 384, while the sum is 25.

The square root of 81011806 is about 9000.6558649912. The cubic root of 81011806 is about 432.6958913036.

The spelling of 81011806 in words is "eighty-one million, eleven thousand, eight hundred six".