81907020 has 288 divisors, whose sum is σ = 297198720. Its totient is φ = 18063360.

The previous prime is 81907019. The next prime is 81907051. The reversal of 81907020 is 2070918.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1153585 + ... + 1153655.

It is an arithmetic number, because the mean of its divisors is an integer number (1031940).

Almost surely, 2^81907020 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 81907020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (148599360).

81907020 is an abundant number, since it is smaller than the sum of its proper divisors (215291700).

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

81907020 is a wasteful number, since it uses less digits than its factorization.

81907020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145 (or 140 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 81907020 is about 9050.2497203116. The cubic root of 81907020 is about 434.2838792010.

Adding to 81907020 its reverse (2070918), we get a palindrome (83977938).

The spelling of 81907020 in words is "eighty-one million, nine hundred seven thousand, twenty".