21321313421 has 8 divisors (see below), whose sum is σ = 22256878464. Its totient is φ = 20386461040.

The previous prime is 21321313411. The next prime is 21321313423. The reversal of 21321313421 is 12431312312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21321313421 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321313423) 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, 116561 + ... + 237126.

It is an arithmetic number, because the mean of its divisors is an integer number (2782109808).

Almost surely, 2^21321313421 is an apocalyptic number.

It is an amenable number.

21321313421 is a deficient number, since it is larger than the sum of its proper divisors (935565043).

21321313421 is a wasteful number, since it uses less digits than its factorization.

21321313421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356331.

The product of its digits is 864, while the sum is 23.

Adding to 21321313421 its reverse (12431312312), we get a palindrome (33752625733).

The spelling of 21321313421 in words is "twenty-one billion, three hundred twenty-one million, three hundred thirteen thousand, four hundred twenty-one".