81650240 has 56 divisors (see below), whose sum is σ = 222211392. Its totient is φ = 27993600.

The previous prime is 81650227. The next prime is 81650267. The reversal of 81650240 is 4205618.

It is a tau number, because it is divible by the number of its divisors (56).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15986 + ... + 20465.

Almost surely, 2^81650240 is an apocalyptic number.

81650240 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81650240 is an abundant number, since it is smaller than the sum of its proper divisors (140561152).

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

81650240 is a wasteful number, since it uses less digits than its factorization.

81650240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36475 (or 36465 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 81650240 is about 9036.0522353515. The cubic root of 81650240 is about 433.8295748276.

Adding to 81650240 its reverse (4205618), we get a palindrome (85855858).

The spelling of 81650240 in words is "eighty-one million, six hundred fifty thousand, two hundred forty".