81855061 has 4 divisors (see below), whose sum is σ = 81886624. Its totient is φ = 81823500.

The previous prime is 81855047. The next prime is 81855073. The reversal of 81855061 is 16055818.

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 a de Polignac number, because none of the positive numbers 2^k-81855061 is a prime.

It is a super-2 number, since 2×81855061² = 13400502022627442, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81855031) 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, 11505 + ... + 17206.

It is an arithmetic number, because the mean of its divisors is an integer number (20471656).

Almost surely, 2^81855061 is an apocalyptic number.

It is an amenable number.

81855061 is a deficient number, since it is larger than the sum of its proper divisors (31563).

81855061 is a wasteful number, since it uses less digits than its factorization.

81855061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31562.

The product of its (nonzero) digits is 9600, while the sum is 34.

The square root of 81855061 is about 9047.3786811430. The cubic root of 81855061 is about 434.1920281840.

The spelling of 81855061 in words is "eighty-one million, eight hundred fifty-five thousand, sixty-one".