812070721 has 16 divisors (see below), whose sum is σ = 1014092928. Its totient is φ = 631756800.

The previous prime is 812070719. The next prime is 812070751. The reversal of 812070721 is 127070218.

It is a 2-Lehmer number, since φ(812070721) divides (812070721-1)².

It is a cyclic number.

It is not a de Polignac number, because 812070721 - 2¹ = 812070719 is a prime.

It is a deceptive number, since it divides R_812070720.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 812070721.

It is not an unprimeable number, because it can be changed into a prime (812070751) 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, 41131 + ... + 57583.

It is an arithmetic number, because the mean of its divisors is an integer number (63380808).

It is a Poulet number, since it divides 2^812070720-1.

Almost surely, 2^812070721 is an apocalyptic number.

812070721 is the 16453-rd octagonal number.

It is an amenable number.

812070721 is a deficient number, since it is larger than the sum of its proper divisors (202022207).

812070721 is a wasteful number, since it uses less digits than its factorization.

812070721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17112.

The product of its (nonzero) digits is 1568, while the sum is 28.

The square root of 812070721 is about 28496.8545808129. The cubic root of 812070721 is about 932.9634229555.

It can be divided in two parts, 81 and 2070721, that multiplied together give a square (167728401 = 12951²).

The spelling of 812070721 in words is "eight hundred twelve million, seventy thousand, seven hundred twenty-one".