81501800 has 24 divisors (see below), whose sum is σ = 189492150. Its totient is φ = 32600640.

The previous prime is 81501779. The next prime is 81501881. The reversal of 81501800 is 810518.

It can be written as a sum of positive squares in 3 ways, for example, as 74200996 + 7300804 = 8614^2 + 2702^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 203555 + ... + 203954.

Almost surely, 2^81501800 is an apocalyptic number.

It is an amenable number.

81501800 is an abundant number, since it is smaller than the sum of its proper divisors (107990350).

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

81501800 is a wasteful number, since it uses less digits than its factorization.

81501800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407525 (or 407516 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 23.

The square root of 81501800 is about 9027.8347348631. The cubic root of 81501800 is about 433.5665148681.

The spelling of 81501800 in words is "eighty-one million, five hundred one thousand, eight hundred".