81921834 has 32 divisors (see below), whose sum is σ = 182787840. Its totient is φ = 27196416.

The previous prime is 81921797. The next prime is 81921857. The reversal of 81921834 is 43812918.

It is a super-2 number, since 2×81921834² = 13422373771847112, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 10927 + ... + 16829.

It is an arithmetic number, because the mean of its divisors is an integer number (5712120).

Almost surely, 2^81921834 is an apocalyptic number.

81921834 is an abundant number, since it is smaller than the sum of its proper divisors (100866006).

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

81921834 is a wasteful number, since it uses less digits than its factorization.

81921834 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6171 (or 6165 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 81921834 is about 9051.0681137643. The cubic root of 81921834 is about 434.3100596739.

The spelling of 81921834 in words is "eighty-one million, nine hundred twenty-one thousand, eight hundred thirty-four".