72128213 has 2 divisors, whose sum is σ = 72128214. Its totient is φ = 72128212.

The previous prime is 72128197. The next prime is 72128219. The reversal of 72128213 is 31282127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49308484 + 22819729 = 7022^2 + 4777^2 .

It is an emirp because it is prime and its reverse (31282127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72128213 - 2⁴ = 72128197 is a prime.

It is a super-2 number, since 2×72128213² = 10404958221146738, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72128219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36064106 + 36064107.

It is an arithmetic number, because the mean of its divisors is an integer number (36064107).

Almost surely, 2^72128213 is an apocalyptic number.

It is an amenable number.

72128213 is a deficient number, since it is larger than the sum of its proper divisors (1).

72128213 is an equidigital number, since it uses as much as digits as its factorization.

72128213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1344, while the sum is 26.

The square root of 72128213 is about 8492.8330373321. The cubic root of 72128213 is about 416.2635568695.

The spelling of 72128213 in words is "seventy-two million, one hundred twenty-eight thousand, two hundred thirteen".