81253620 has 144 divisors (see below), whose sum is σ = 286715520. Its totient is φ = 18240768.

The previous prime is 81253619. The next prime is 81253631. The reversal of 81253620 is 2635218.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 73794 + ... + 74886.

It is an arithmetic number, because the mean of its divisors is an integer number (1991080).

Almost surely, 2^81253620 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 81253620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (143357760).

81253620 is an abundant number, since it is smaller than the sum of its proper divisors (205461900).

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

81253620 is a wasteful number, since it uses less digits than its factorization.

81253620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1174 (or 1169 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 81253620 is about 9014.0789878944. The cubic root of 81253620 is about 433.1259849556.

Adding to 81253620 its reverse (2635218), we get a palindrome (83888838).

The spelling of 81253620 in words is "eighty-one million, two hundred fifty-three thousand, six hundred twenty".