21111220201 has 4 divisors (see below), whose sum is σ = 21113551504. Its totient is φ = 21108888900.

The previous prime is 21111220199. The next prime is 21111220223. The reversal of 21111220201 is 10202211112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21111220201 - 2¹ = 21111220199 is a prime.

It is a super-2 number, since 2×21111220201² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111220001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1152015 + ... + 1170196.

It is an arithmetic number, because the mean of its divisors is an integer number (5278387876).

Almost surely, 2^21111220201 is an apocalyptic number.

It is an amenable number.

21111220201 is a deficient number, since it is larger than the sum of its proper divisors (2331303).

21111220201 is an equidigital number, since it uses as much as digits as its factorization.

21111220201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2331302.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21111220201 its reverse (10202211112), we get a palindrome (31313431313).

The spelling of 21111220201 in words is "twenty-one billion, one hundred eleven million, two hundred twenty thousand, two hundred one".