21124201321 has 4 divisors (see below), whose sum is σ = 21258750532. Its totient is φ = 20989652112.

The previous prime is 21124201313. The next prime is 21124201337. The reversal of 21124201321 is 12310242112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7090482025 + 14033719296 = 84205^2 + 118464^2 .

It is a cyclic number.

It is not a de Polignac number, because 21124201321 - 2³ = 21124201313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21124301321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67274370 + ... + 67274683.

It is an arithmetic number, because the mean of its divisors is an integer number (5314687633).

Almost surely, 2^21124201321 is an apocalyptic number.

It is an amenable number.

21124201321 is a deficient number, since it is larger than the sum of its proper divisors (134549211).

21124201321 is a wasteful number, since it uses less digits than its factorization.

21124201321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134549210.

The product of its (nonzero) digits is 192, while the sum is 19.

Adding to 21124201321 its reverse (12310242112), we get a palindrome (33434443433).

The spelling of 21124201321 in words is "twenty-one billion, one hundred twenty-four million, two hundred one thousand, three hundred twenty-one".