81942644 has 24 divisors (see below), whose sum is σ = 164084928. Its totient is φ = 35075520.

The previous prime is 81942617. The next prime is 81942673. The reversal of 81942644 is 44624918.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 81942598 and 81942607.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34784 + ... + 37064.

It is an arithmetic number, because the mean of its divisors is an integer number (6836872).

Almost surely, 2^81942644 is an apocalyptic number.

It is an amenable number.

81942644 is an abundant number, since it is smaller than the sum of its proper divisors (82142284).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81942644 is a wasteful number, since it uses less digits than its factorization.

81942644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3575 (or 3573 counting only the distinct ones).

The product of its digits is 55296, while the sum is 38.

The square root of 81942644 is about 9052.2176288465. The cubic root of 81942644 is about 434.3468314221.

The spelling of 81942644 in words is "eighty-one million, nine hundred forty-two thousand, six hundred forty-four".