81225570001 has 9 divisors (see below), whose sum is σ = 82051477641. Its totient is φ = 80407902132.

The previous prime is 81225569921. The next prime is 81225570031. The reversal of 81225570001 is 10007552218.

The square root of 81225570001 is 285001.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 81225570001 - 2²³ = 81217181393 is a prime.

It is a super-2 number, since 2×81225570001² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81225570031) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 29353720 + ... + 29356486.

It is an arithmetic number, because the mean of its divisors is an integer number (9116830849).

Almost surely, 2^81225570001 is an apocalyptic number.

81225570001 is the 285001-st square number.

81225570001 is the 142501-st centered octagonal number.

It is an amenable number.

81225570001 is a deficient number, since it is larger than the sum of its proper divisors (825907640).

81225570001 is an frugal number, since it uses more digits than its factorization.

81225570001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5740 (or 2870 counting only the distinct ones).

The product of its (nonzero) digits is 5600, while the sum is 31.

The spelling of 81225570001 in words is "eighty-one billion, two hundred twenty-five million, five hundred seventy thousand, one".