21435020321 has 16 divisors (see below), whose sum is σ = 25219712448. Its totient is φ = 17960779200.

The previous prime is 21435020303. The next prime is 21435020323. The reversal of 21435020321 is 12302053412.

It is a de Polignac number, because none of the positive numbers 2^k-21435020321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21435020323) 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, 13895 + ... + 207516.

It is an arithmetic number, because the mean of its divisors is an integer number (1576232028).

Almost surely, 2^21435020321 is an apocalyptic number.

It is an amenable number.

21435020321 is a deficient number, since it is larger than the sum of its proper divisors (3784692127).

21435020321 is a wasteful number, since it uses less digits than its factorization.

21435020321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222112.

The product of its (nonzero) digits is 1440, while the sum is 23.

Adding to 21435020321 its reverse (12302053412), we get a palindrome (33737073733).

The spelling of 21435020321 in words is "twenty-one billion, four hundred thirty-five million, twenty thousand, three hundred twenty-one".