21412240021 has 4 divisors (see below), whose sum is σ = 21608682700. Its totient is φ = 21215797344.

The previous prime is 21412240009. The next prime is 21412240081. The reversal of 21412240021 is 12004221412.

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 19401704100 + 2010535921 = 139290^2 + 44839^2 .

It is a cyclic number.

It is not a de Polignac number, because 21412240021 - 2²¹ = 21410142869 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21412240081) 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, 98221176 + ... + 98221393.

It is an arithmetic number, because the mean of its divisors is an integer number (5402170675).

Almost surely, 2^21412240021 is an apocalyptic number.

It is an amenable number.

21412240021 is a deficient number, since it is larger than the sum of its proper divisors (196442679).

21412240021 is a wasteful number, since it uses less digits than its factorization.

21412240021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196442678.

The product of its (nonzero) digits is 256, while the sum is 19.

Adding to 21412240021 its reverse (12004221412), we get a palindrome (33416461433).

The spelling of 21412240021 in words is "twenty-one billion, four hundred twelve million, two hundred forty thousand, twenty-one".