72782221 has 2 divisors, whose sum is σ = 72782222. Its totient is φ = 72782220.

The previous prime is 72782201. The next prime is 72782231. The reversal of 72782221 is 12228727.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 38266596 + 34515625 = 6186^2 + 5875^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72782221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72782201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36391110 + 36391111.

It is an arithmetic number, because the mean of its divisors is an integer number (36391111).

Almost surely, 2^72782221 is an apocalyptic number.

It is an amenable number.

72782221 is a deficient number, since it is larger than the sum of its proper divisors (1).

72782221 is an equidigital number, since it uses as much as digits as its factorization.

72782221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6272, while the sum is 31.

The square root of 72782221 is about 8531.2496739927. The cubic root of 72782221 is about 417.5179018702.

The spelling of 72782221 in words is "seventy-two million, seven hundred eighty-two thousand, two hundred twenty-one".