221657939 has 2 divisors, whose sum is σ = 221657940. Its totient is φ = 221657938.

The previous prime is 221657911. The next prime is 221657977. The reversal of 221657939 is 939756122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221657939 - 2¹² = 221653843 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 221657939.

It is not a weakly prime, because it can be changed into another prime (221657039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110828969 + 110828970.

It is an arithmetic number, because the mean of its divisors is an integer number (110828970).

Almost surely, 2^221657939 is an apocalyptic number.

221657939 is a deficient number, since it is larger than the sum of its proper divisors (1).

221657939 is an equidigital number, since it uses as much as digits as its factorization.

221657939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 204120, while the sum is 44.

The square root of 221657939 is about 14888.1811850877. The cubic root of 221657939 is about 605.1937443829.

The spelling of 221657939 in words is "two hundred twenty-one million, six hundred fifty-seven thousand, nine hundred thirty-nine".