812501721 has 12 divisors (see below), whose sum is σ = 1174606420. Its totient is φ = 541209600.

The previous prime is 812501707. The next prime is 812501741. The reversal of 812501721 is 127105218.

It can be written as a sum of positive squares in 2 ways, for example, as 175191696 + 637310025 = 13236^2 + 25245^2 .

It is not a de Polignac number, because 812501721 - 2¹⁰ = 812500697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (812501741) 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, 26776 + ... + 48393.

Almost surely, 2^812501721 is an apocalyptic number.

It is an amenable number.

812501721 is a deficient number, since it is larger than the sum of its proper divisors (362104699).

812501721 is a wasteful number, since it uses less digits than its factorization.

812501721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76376 (or 76373 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 27.

The square root of 812501721 is about 28504.4158157995. The cubic root of 812501721 is about 933.1284480399.

Adding to 812501721 its reverse (127105218), we get a palindrome (939606939).

The spelling of 812501721 in words is "eight hundred twelve million, five hundred one thousand, seven hundred twenty-one".