81856419 has 4 divisors (see below), whose sum is σ = 109141896. Its totient is φ = 54570944.

The previous prime is 81856381. The next prime is 81856429. The reversal of 81856419 is 91465818.

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 81856419 - 2¹⁶ = 81790883 is a prime.

It is a super-2 number, since 2×81856419² = 13400946663007122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81856429) 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, 13642734 + ... + 13642739.

It is an arithmetic number, because the mean of its divisors is an integer number (27285474).

Almost surely, 2^81856419 is an apocalyptic number.

81856419 is a deficient number, since it is larger than the sum of its proper divisors (27285477).

81856419 is a wasteful number, since it uses less digits than its factorization.

81856419 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27285476.

The product of its digits is 69120, while the sum is 42.

The square root of 81856419 is about 9047.4537301939. The cubic root of 81856419 is about 434.1944292961.

The spelling of 81856419 in words is "eighty-one million, eight hundred fifty-six thousand, four hundred nineteen".