81821043 has 8 divisors (see below), whose sum is σ = 121216400. Its totient is φ = 54547344.

The previous prime is 81821041. The next prime is 81821053. The reversal of 81821043 is 34012818.

It is not a de Polignac number, because 81821043 - 2¹ = 81821041 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 3030409 = 81821043 / (8 + 1 + 8 + 2 + 1 + 0 + 4 + 3).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81820998 and 81821016.

It is not an unprimeable number, because it can be changed into a prime (81821041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1515178 + ... + 1515231.

It is an arithmetic number, because the mean of its divisors is an integer number (15152050).

Almost surely, 2^81821043 is an apocalyptic number.

81821043 is a deficient number, since it is larger than the sum of its proper divisors (39395357).

81821043 is a wasteful number, since it uses less digits than its factorization.

81821043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3030418 (or 3030412 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 81821043 is about 9045.4984937260. The cubic root of 81821043 is about 434.1318714842.

The spelling of 81821043 in words is "eighty-one million, eight hundred twenty-one thousand, forty-three".