81321509838 has 16 divisors (see below), whose sum is σ = 164933767296. Its totient is φ = 26725378680.

The previous prime is 81321509833. The next prime is 81321509851. The reversal of 81321509838 is 83890512318.

It is a super-2 number, since 2×81321509838² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81321509833) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 95447356 + ... + 95448207.

It is an arithmetic number, because the mean of its divisors is an integer number (10308360456).

Almost surely, 2^81321509838 is an apocalyptic number.

81321509838 is an abundant number, since it is smaller than the sum of its proper divisors (83612257458).

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

81321509838 is a wasteful number, since it uses less digits than its factorization.

81321509838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190895639.

The product of its (nonzero) digits is 414720, while the sum is 48.

The spelling of 81321509838 in words is "eighty-one billion, three hundred twenty-one million, five hundred nine thousand, eight hundred thirty-eight".