81930644 has 12 divisors (see below), whose sum is σ = 148003968. Its totient is φ = 39643800.

The previous prime is 81930643. The next prime is 81930647. The reversal of 81930644 is 44603918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81930643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 330242 + ... + 330489.

It is an arithmetic number, because the mean of its divisors is an integer number (12333664).

Almost surely, 2^81930644 is an apocalyptic number.

It is an amenable number.

81930644 is a deficient number, since it is larger than the sum of its proper divisors (66073324).

81930644 is a wasteful number, since it uses less digits than its factorization.

81930644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 660766 (or 660764 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 81930644 is about 9051.5547835717. The cubic root of 81930644 is about 434.3256279064.

The spelling of 81930644 in words is "eighty-one million, nine hundred thirty thousand, six hundred forty-four".