81245680 has 20 divisors (see below), whose sum is σ = 188896392. Its totient is φ = 32498240.

The previous prime is 81245663. The next prime is 81245687. The reversal of 81245680 is 8654218.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81245687) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 507706 + ... + 507865.

Almost surely, 2^81245680 is an apocalyptic number.

81245680 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81245680 is an abundant number, since it is smaller than the sum of its proper divisors (107650712).

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

81245680 is a wasteful number, since it uses less digits than its factorization.

81245680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1015584 (or 1015578 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 34.

The square root of 81245680 is about 9013.6385549899. The cubic root of 81245680 is about 433.1118763233. Note that the first 3 decimals are identical.

Adding to 81245680 its reverse (8654218), we get a palindrome (89899898).

The spelling of 81245680 in words is "eighty-one million, two hundred forty-five thousand, six hundred eighty".