812581020 has 36 divisors (see below), whose sum is σ = 2464829640. Its totient is φ = 216688224.

The previous prime is 812580991. The next prime is 812581027. The reversal of 812581020 is 20185218.

812581020 is a `hidden beast` number, since 81 + 2 + 581 + 0 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (812581027) 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, 2256990 + ... + 2257349.

It is an arithmetic number, because the mean of its divisors is an integer number (68467490).

Almost surely, 2^812581020 is an apocalyptic number.

It is an amenable number.

812581020 is an abundant number, since it is smaller than the sum of its proper divisors (1652248620).

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

812581020 is a wasteful number, since it uses less digits than its factorization.

812581020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4514354 (or 4514349 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 812581020 is about 28505.8067768657. The cubic root of 812581020 is about 933.1588043841.

The spelling of 812581020 in words is "eight hundred twelve million, five hundred eighty-one thousand, twenty".