81900285 has 16 divisors (see below), whose sum is σ = 131153856. Its totient is φ = 43642368.

The previous prime is 81900257. The next prime is 81900389. The reversal of 81900285 is 58200918.

It is a happy number.

It is not a de Polignac number, because 81900285 - 2¹¹ = 81898237 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28902 + ... + 31608.

It is an arithmetic number, because the mean of its divisors is an integer number (8197116).

Almost surely, 2^81900285 is an apocalyptic number.

It is an amenable number.

81900285 is a deficient number, since it is larger than the sum of its proper divisors (49253571).

81900285 is a wasteful number, since it uses less digits than its factorization.

81900285 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4732.

The product of its (nonzero) digits is 5760, while the sum is 33.

The square root of 81900285 is about 9049.8776234820. The cubic root of 81900285 is about 434.2719755322.

The spelling of 81900285 in words is "eighty-one million, nine hundred thousand, two hundred eighty-five".