81039420 has 192 divisors, whose sum is σ = 314496000. Its totient is φ = 16830720.

The previous prime is 81039379. The next prime is 81039433. The reversal of 81039420 is 2493018.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

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 63 ways as a sum of consecutive naturals, for example, 40606 + ... + 42554.

It is an arithmetic number, because the mean of its divisors is an integer number (1638000).

Almost surely, 2^81039420 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81039420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (157248000).

81039420 is an abundant number, since it is smaller than the sum of its proper divisors (233456580).

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

81039420 is a wasteful number, since it uses less digits than its factorization.

81039420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1985 (or 1977 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 81039420 is about 9002.1897336148. The cubic root of 81039420 is about 432.7450491881.

The spelling of 81039420 in words is "eighty-one million, thirty-nine thousand, four hundred twenty".