21221201001 has 256 divisors, whose sum is σ = 41341353984. Its totient is φ = 9331200000.

The previous prime is 21221200991. The next prime is 21221201021. The reversal of 21221201001 is 10010212212.

It is not a de Polignac number, because 21221201001 - 2¹⁵ = 21221168233 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21221201021) 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 255 ways as a sum of consecutive naturals, for example, 210110851 + ... + 210110951.

It is an arithmetic number, because the mean of its divisors is an integer number (161489664).

Almost surely, 2^21221201001 is an apocalyptic number.

21221201001 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21221201001 is a deficient number, since it is larger than the sum of its proper divisors (20120152983).

21221201001 is a wasteful number, since it uses less digits than its factorization.

21221201001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 264.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21221201001 its reverse (10010212212), we get a palindrome (31231413213).

It can be divided in two parts, 21221 and 201001, that added together give a palindrome (222222).

The spelling of 21221201001 in words is "twenty-one billion, two hundred twenty-one million, two hundred one thousand, one".