21420220421 has 8 divisors (see below), whose sum is σ = 21716615424. Its totient is φ = 21123905760.

The previous prime is 21420220403. The next prime is 21420220427. The reversal of 21420220421 is 12402202412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21420220421 - 2¹⁰ = 21420219397 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21420220393 and 21420220402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420220427) 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 7 ways as a sum of consecutive naturals, for example, 687830 + ... + 718296.

It is an arithmetic number, because the mean of its divisors is an integer number (2714576928).

Almost surely, 2^21420220421 is an apocalyptic number.

It is an amenable number.

21420220421 is a deficient number, since it is larger than the sum of its proper divisors (296395003).

21420220421 is an equidigital number, since it uses as much as digits as its factorization.

21420220421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40171.

The product of its (nonzero) digits is 512, while the sum is 20.

Adding to 21420220421 its reverse (12402202412), we get a palindrome (33822422833).

The spelling of 21420220421 in words is "twenty-one billion, four hundred twenty million, two hundred twenty thousand, four hundred twenty-one".