221951287 has 2 divisors, whose sum is σ = 221951288. Its totient is φ = 221951286.

The previous prime is 221951243. The next prime is 221951329. The reversal of 221951287 is 782159122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221951287 - 2¹⁵ = 221918519 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221951207) 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 as a sum of consecutive naturals, namely, 110975643 + 110975644.

It is an arithmetic number, because the mean of its divisors is an integer number (110975644).

Almost surely, 2^221951287 is an apocalyptic number.

221951287 is a deficient number, since it is larger than the sum of its proper divisors (1).

221951287 is an equidigital number, since it uses as much as digits as its factorization.

221951287 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 37.

The square root of 221951287 is about 14898.0296348208. The cubic root of 221951287 is about 605.4606031832.

The spelling of 221951287 in words is "two hundred twenty-one million, nine hundred fifty-one thousand, two hundred eighty-seven".