21421020021 has 8 divisors (see below), whose sum is σ = 28625834400. Its totient is φ = 14248442832.

The previous prime is 21421019993. The next prime is 21421020041. The reversal of 21421020021 is 12002012412.

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

It is not a de Polignac number, because 21421020021 - 2⁹ = 21421019509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421020041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8057746 + ... + 8060403.

It is an arithmetic number, because the mean of its divisors is an integer number (3578229300).

Almost surely, 2^21421020021 is an apocalyptic number.

It is an amenable number.

21421020021 is a deficient number, since it is larger than the sum of its proper divisors (7204814379).

21421020021 is a wasteful number, since it uses less digits than its factorization.

21421020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16118595.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21421020021 its reverse (12002012412), we get a palindrome (33423032433).

The spelling of 21421020021 in words is "twenty-one billion, four hundred twenty-one million, twenty thousand, twenty-one".