81819537 has 8 divisors (see below), whose sum is σ = 109374720. Its totient is φ = 54405360.

The previous prime is 81819523. The next prime is 81819593. The reversal of 81819537 is 73591818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81819537 - 2⁶ = 81819473 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81819337) 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 7 ways as a sum of consecutive naturals, for example, 33889 + ... + 36222.

It is an arithmetic number, because the mean of its divisors is an integer number (13671840).

Almost surely, 2^81819537 is an apocalyptic number.

It is an amenable number.

81819537 is a deficient number, since it is larger than the sum of its proper divisors (27555183).

81819537 is a wasteful number, since it uses less digits than its factorization.

81819537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70503.

The product of its digits is 60480, while the sum is 42.

The square root of 81819537 is about 9045.4152475163. The cubic root of 81819537 is about 434.1292079207.

The spelling of 81819537 in words is "eighty-one million, eight hundred nineteen thousand, five hundred thirty-seven".