21400220221 has 4 divisors (see below), whose sum is σ = 21401470944. Its totient is φ = 21398969500.

The previous prime is 21400220213. The next prime is 21400220243. The reversal of 21400220221 is 12202200412.

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 21400220221 - 2³ = 21400220213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21400220195 and 21400220204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21400200221) 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, 599335 + ... + 634036.

It is an arithmetic number, because the mean of its divisors is an integer number (5350367736).

Almost surely, 2^21400220221 is an apocalyptic number.

It is an amenable number.

21400220221 is a deficient number, since it is larger than the sum of its proper divisors (1250723).

21400220221 is a wasteful number, since it uses less digits than its factorization.

21400220221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1250722.

The product of its (nonzero) digits is 128, while the sum is 16.

Adding to 21400220221 its reverse (12202200412), we get a palindrome (33602420633).

The spelling of 21400220221 in words is "twenty-one billion, four hundred million, two hundred twenty thousand, two hundred twenty-one".