72866221 has 2 divisors, whose sum is σ = 72866222. Its totient is φ = 72866220.

The previous prime is 72866219. The next prime is 72866243. The reversal of 72866221 is 12266827.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52490025 + 20376196 = 7245^2 + 4514^2 .

It is an emirp because it is prime and its reverse (12266827) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72866221 - 2¹ = 72866219 is a prime.

Together with 72866219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72806221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36433110 + 36433111.

It is an arithmetic number, because the mean of its divisors is an integer number (36433111).

Almost surely, 2^72866221 is an apocalyptic number.

It is an amenable number.

72866221 is a deficient number, since it is larger than the sum of its proper divisors (1).

72866221 is an equidigital number, since it uses as much as digits as its factorization.

72866221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16128, while the sum is 34.

The square root of 72866221 is about 8536.1713314577. The cubic root of 72866221 is about 417.6784631519.

The spelling of 72866221 in words is "seventy-two million, eight hundred sixty-six thousand, two hundred twenty-one".