81353620 has 24 divisors (see below), whose sum is σ = 172152288. Its totient is φ = 32292000.

The previous prime is 81353617. The next prime is 81353627. The reversal of 81353620 is 2635318.

It is a super-2 number, since 2×81353620² = 13236822974208800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81353627) 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, 12906 + ... + 18145.

It is an arithmetic number, because the mean of its divisors is an integer number (7173012).

Almost surely, 2^81353620 is an apocalyptic number.

It is an amenable number.

81353620 is an abundant number, since it is smaller than the sum of its proper divisors (90798668).

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

81353620 is a wasteful number, since it uses less digits than its factorization.

81353620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31191 (or 31189 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 81353620 is about 9019.6241606843. The cubic root of 81353620 is about 433.3035969075.

Adding to 81353620 its reverse (2635318), we get a palindrome (83988938).

The spelling of 81353620 in words is "eighty-one million, three hundred fifty-three thousand, six hundred twenty".