81810570 has 32 divisors (see below), whose sum is σ = 196606080. Its totient is φ = 21787200.

The previous prime is 81810559. The next prime is 81810571. The reversal of 81810570 is 7501818.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (81810571) 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, 30795 + ... + 33345.

It is an arithmetic number, because the mean of its divisors is an integer number (6143940).

Almost surely, 2^81810570 is an apocalyptic number.

81810570 is an abundant number, since it is smaller than the sum of its proper divisors (114795510).

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

81810570 is a wasteful number, since it uses less digits than its factorization.

81810570 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3630.

The product of its (nonzero) digits is 2240, while the sum is 30.

The square root of 81810570 is about 9044.9195684649. The cubic root of 81810570 is about 434.1133478993.

The spelling of 81810570 in words is "eighty-one million, eight hundred ten thousand, five hundred seventy".