21273420421 has 16 divisors (see below), whose sum is σ = 23290504128. Its totient is φ = 19270326400.

The previous prime is 21273420419. The next prime is 21273420473. The reversal of 21273420421 is 12402437212.

It is a cyclic number.

It is not a de Polignac number, because 21273420421 - 2¹ = 21273420419 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21273420421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21273420481) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3877146 + ... + 3882628.

It is an arithmetic number, because the mean of its divisors is an integer number (1455656508).

Almost surely, 2^21273420421 is an apocalyptic number.

It is an amenable number.

21273420421 is a deficient number, since it is larger than the sum of its proper divisors (2017083707).

21273420421 is a wasteful number, since it uses less digits than its factorization.

21273420421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6692.

The product of its (nonzero) digits is 5376, while the sum is 28.

Adding to 21273420421 its reverse (12402437212), we get a palindrome (33675857633).

The spelling of 21273420421 in words is "twenty-one billion, two hundred seventy-three million, four hundred twenty thousand, four hundred twenty-one".