81005631819 has 16 divisors (see below), whose sum is σ = 123556680192. Its totient is φ = 46244109888.

The previous prime is 81005631781. The next prime is 81005631823. The reversal of 81005631819 is 91813650018.

It is not a de Polignac number, because 81005631819 - 2⁹ = 81005631307 is a prime.

It is a super-2 number, since 2×81005631819² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81005631019) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1845399 + ... + 1888784.

It is an arithmetic number, because the mean of its divisors is an integer number (7722292512).

Almost surely, 2^81005631819 is an apocalyptic number.

81005631819 is a deficient number, since it is larger than the sum of its proper divisors (42551048373).

81005631819 is a wasteful number, since it uses less digits than its factorization.

81005631819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3735226.

The product of its (nonzero) digits is 51840, while the sum is 42.

The spelling of 81005631819 in words is "eighty-one billion, five million, six hundred thirty-one thousand, eight hundred nineteen".