221421651601 has 4 divisors (see below), whose sum is σ = 225051514804. Its totient is φ = 217791788400.

The previous prime is 221421651589. The next prime is 221421651707. The reversal of 221421651601 is 106156124122.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14374811025 + 207046840576 = 119895^2 + 455024^2 .

It is a cyclic number.

It is not a de Polignac number, because 221421651601 - 2⁵ = 221421651569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221421652601) 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 in 3 ways as a sum of consecutive naturals, for example, 1814931510 + ... + 1814931631.

It is an arithmetic number, because the mean of its divisors is an integer number (56262878701).

Almost surely, 2^221421651601 is an apocalyptic number.

It is an amenable number.

221421651601 is a deficient number, since it is larger than the sum of its proper divisors (3629863203).

221421651601 is an equidigital number, since it uses as much as digits as its factorization.

221421651601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3629863202.

The product of its (nonzero) digits is 5760, while the sum is 31.

Adding to 221421651601 its reverse (106156124122), we get a palindrome (327577775723).

The spelling of 221421651601 in words is "two hundred twenty-one billion, four hundred twenty-one million, six hundred fifty-one thousand, six hundred one".