81025920 has 192 divisors, whose sum is σ = 290712240. Its totient is φ = 21565440.

The previous prime is 81025891. The next prime is 81025949. The reversal of 81025920 is 2952018.

It is an interprime number because it is at equal distance from previous prime (81025891) and next prime (81025949).

It is a tau number, because it is divible by the number of its divisors (192).

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 23 ways as a sum of consecutive naturals, for example, 155260 + ... + 155780.

Almost surely, 2^81025920 is an apocalyptic number.

81025920 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81025920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (145356120).

81025920 is an abundant number, since it is smaller than the sum of its proper divisors (209686320).

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

81025920 is an equidigital number, since it uses as much as digits as its factorization.

81025920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 555 (or 531 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 81025920 is about 9001.4398848184. The cubic root of 81025920 is about 432.7210181565.

Adding to 81025920 its reverse (2952018), we get a palindrome (83977938).

The spelling of 81025920 in words is "eighty-one million, twenty-five thousand, nine hundred twenty".