81099825 has 12 divisors (see below), whose sum is σ = 134085168. Its totient is φ = 43253200.

The previous prime is 81099803. The next prime is 81099827. The reversal of 81099825 is 52899018.

It is a happy number.

It is not a de Polignac number, because 81099825 - 2⁹ = 81099313 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81099827) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 540591 + ... + 540740.

It is an arithmetic number, because the mean of its divisors is an integer number (11173764).

Almost surely, 2^81099825 is an apocalyptic number.

It is an amenable number.

81099825 is a deficient number, since it is larger than the sum of its proper divisors (52985343).

81099825 is a wasteful number, since it uses less digits than its factorization.

81099825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1081344 (or 1081339 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 42.

The square root of 81099825 is about 9005.5441257039. The cubic root of 81099825 is about 432.8525420299.

The spelling of 81099825 in words is "eighty-one million, ninety-nine thousand, eight hundred twenty-five".