81910990 has 32 divisors (see below), whose sum is σ = 173942784. Its totient is φ = 27177120.

The previous prime is 81910979. The next prime is 81910991. The reversal of 81910990 is 9901918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81910991) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16704 + ... + 21043.

It is an arithmetic number, because the mean of its divisors is an integer number (5435712).

Almost surely, 2^81910990 is an apocalyptic number.

81910990 is an abundant number, since it is smaller than the sum of its proper divisors (92031794).

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

81910990 is a wasteful number, since it uses less digits than its factorization.

81910990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37792.

The product of its (nonzero) digits is 5832, while the sum is 37.

The square root of 81910990 is about 9050.4690486184. The cubic root of 81910990 is about 434.2908956087.

The spelling of 81910990 in words is "eighty-one million, nine hundred ten thousand, nine hundred ninety".