221871901 has 2 divisors, whose sum is σ = 221871902. Its totient is φ = 221871900.

The previous prime is 221871899. The next prime is 221871931. The reversal of 221871901 is 109178122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 165636900 + 56235001 = 12870^2 + 7499^2 .

It is a cyclic number.

It is not a de Polignac number, because 221871901 - 2¹ = 221871899 is a prime.

Together with 221871899, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221871931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110935950 + 110935951.

It is an arithmetic number, because the mean of its divisors is an integer number (110935951).

Almost surely, 2^221871901 is an apocalyptic number.

It is an amenable number.

221871901 is a deficient number, since it is larger than the sum of its proper divisors (1).

221871901 is an equidigital number, since it uses as much as digits as its factorization.

221871901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2016, while the sum is 31.

The square root of 221871901 is about 14895.3650844818. The cubic root of 221871901 is about 605.3884089227.

The spelling of 221871901 in words is "two hundred twenty-one million, eight hundred seventy-one thousand, nine hundred one".