81819964 has 12 divisors (see below), whose sum is σ = 143977288. Its totient is φ = 40683600.

The previous prime is 81819953. The next prime is 81819967. The reversal of 81819964 is 46991818.

It is a super-2 number, since 2×81819964² = 13389013017922592, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81819967) 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 3 ways as a sum of consecutive naturals, for example, 55782 + ... + 57229.

Almost surely, 2^81819964 is an apocalyptic number.

It is an amenable number.

81819964 is a deficient number, since it is larger than the sum of its proper divisors (62157324).

81819964 is a wasteful number, since it uses less digits than its factorization.

81819964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113196 (or 113194 counting only the distinct ones).

The product of its digits is 124416, while the sum is 46.

The square root of 81819964 is about 9045.4388506031. The cubic root of 81819964 is about 434.1299631310.

It can be divided in two parts, 8181 and 9964, that added together give a triangular number (18145 = T₁₉₀).

The spelling of 81819964 in words is "eighty-one million, eight hundred nineteen thousand, nine hundred sixty-four".