221211220021 has 24 divisors (see below), whose sum is σ = 244666340352. Its totient is φ = 199850481600.

The previous prime is 221211219961. The next prime is 221211220031. The reversal of 221211220021 is 120022112122.

It is a happy number.

It is not a de Polignac number, because 221211220021 - 2²⁹ = 220674349109 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221211219977 and 221211220004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221211220031) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13013890 + ... + 13030876.

It is an arithmetic number, because the mean of its divisors is an integer number (10194430848).

Almost surely, 2^221211220021 is an apocalyptic number.

It is an amenable number.

221211220021 is a deficient number, since it is larger than the sum of its proper divisors (23455120331).

221211220021 is a wasteful number, since it uses less digits than its factorization.

221211220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17673 (or 17662 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 221211220021 its reverse (120022112122), we get a palindrome (341233332143).

The spelling of 221211220021 in words is "two hundred twenty-one billion, two hundred eleven million, two hundred twenty thousand, twenty-one".