7255217721 has 32 divisors (see below), whose sum is σ = 10473615360. Its totient is φ = 4450777344.

The previous prime is 7255217719. The next prime is 7255217741. The reversal of 7255217721 is 1277125527.

It is not a de Polignac number, because 7255217721 - 2¹ = 7255217719 is a prime.

It is a super-2 number, since 2×7255217721² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 7255217721.

It is not an unprimeable number, because it can be changed into a prime (7255217701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 406246 + ... + 423728.

It is an arithmetic number, because the mean of its divisors is an integer number (327300480).

Almost surely, 2^7255217721 is an apocalyptic number.

It is an amenable number.

7255217721 is a deficient number, since it is larger than the sum of its proper divisors (3218397639).

7255217721 is a wasteful number, since it uses less digits than its factorization.

7255217721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17685.

The product of its digits is 68600, while the sum is 39.

The square root of 7255217721 is about 85177.5658316202. The cubic root of 7255217721 is about 1935.9025113730.

The spelling of 7255217721 in words is "seven billion, two hundred fifty-five million, two hundred seventeen thousand, seven hundred twenty-one".