221891851 has 2 divisors, whose sum is σ = 221891852. Its totient is φ = 221891850.

The previous prime is 221891821. The next prime is 221891897. The reversal of 221891851 is 158198122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221891851 - 2⁷ = 221891723 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221891851.

It is not a weakly prime, because it can be changed into another prime (221891821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110945925 + 110945926.

It is an arithmetic number, because the mean of its divisors is an integer number (110945926).

Almost surely, 2^221891851 is an apocalyptic number.

221891851 is a deficient number, since it is larger than the sum of its proper divisors (1).

221891851 is an equidigital number, since it uses as much as digits as its factorization.

221891851 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11520, while the sum is 37.

The square root of 221891851 is about 14896.0347408295. The cubic root of 221891851 is about 605.4065532314.

The spelling of 221891851 in words is "two hundred twenty-one million, eight hundred ninety-one thousand, eight hundred fifty-one".