221001421 has 2 divisors, whose sum is σ = 221001422. Its totient is φ = 221001420.

The previous prime is 221001409. The next prime is 221001437. The reversal of 221001421 is 124100122.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 220849321 + 152100 = 14861^2 + 390^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221001421 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221001461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110500710 + 110500711.

It is an arithmetic number, because the mean of its divisors is an integer number (110500711).

Almost surely, 2^221001421 is an apocalyptic number.

It is an amenable number.

221001421 is a deficient number, since it is larger than the sum of its proper divisors (1).

221001421 is an equidigital number, since it uses as much as digits as its factorization.

221001421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 221001421 is about 14866.1165406437. The cubic root of 221001421 is about 604.5956554184.

Adding to 221001421 its reverse (124100122), we get a palindrome (345101543).

The spelling of 221001421 in words is "two hundred twenty-one million, one thousand, four hundred twenty-one".