2156072221 has 2 divisors, whose sum is σ = 2156072222. Its totient is φ = 2156072220.

The previous prime is 2156072197. The next prime is 2156072249. The reversal of 2156072221 is 1222706512.

It is an a-pointer prime, because the next prime (2156072249) can be obtained adding 2156072221 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2071524196 + 84548025 = 45514^2 + 9195^2 .

It is a cyclic number.

It is not a de Polignac number, because 2156072221 - 2⁵ = 2156072189 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2156072221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2156072021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1078036110 + 1078036111.

It is an arithmetic number, because the mean of its divisors is an integer number (1078036111).

Almost surely, 2^2156072221 is an apocalyptic number.

It is an amenable number.

2156072221 is a deficient number, since it is larger than the sum of its proper divisors (1).

2156072221 is an equidigital number, since it uses as much as digits as its factorization.

2156072221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 2156072221 is about 46433.5247531350. The cubic root of 2156072221 is about 1291.8768068198.

Adding to 2156072221 its reverse (1222706512), we get a palindrome (3378778733).

The spelling of 2156072221 in words is "two billion, one hundred fifty-six million, seventy-two thousand, two hundred twenty-one".