81289870 has 16 divisors (see below), whose sum is σ = 146503728. Its totient is φ = 32475520.

The previous prime is 81289867. The next prime is 81289877. The reversal of 81289870 is 7898218.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81289877) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4197 + ... + 13423.

It is an arithmetic number, because the mean of its divisors is an integer number (9156483).

Almost surely, 2^81289870 is an apocalyptic number.

81289870 is a deficient number, since it is larger than the sum of its proper divisors (65213858).

81289870 is a wasteful number, since it uses less digits than its factorization.

81289870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10115.

The product of its (nonzero) digits is 64512, while the sum is 43.

The square root of 81289870 is about 9016.0895070979. The cubic root of 81289870 is about 433.1903861176.

The spelling of 81289870 in words is "eighty-one million, two hundred eighty-nine thousand, eight hundred seventy".